diff --git a/mod/assignment/lib.php b/mod/assignment/lib.php
index 6e3af37f17f..7f02446f2de 100644
--- a/mod/assignment/lib.php
+++ b/mod/assignment/lib.php
@@ -326,14 +326,23 @@ class assignment_base {
         // of the new instance.
 
         $assignment->timemodified = time();
-        $assignment->timedue = make_timestamp($assignment->dueyear, $assignment->duemonth, 
-                                              $assignment->dueday, $assignment->duehour, 
-                                              $assignment->dueminute);
-        $assignment->timeavailable = make_timestamp($assignment->availableyear, $assignment->availablemonth, 
-                                                    $assignment->availableday, $assignment->availablehour, 
-                                                    $assignment->availableminute);
+        if (empty($assignment->dueenable)) {
+            $assignment->timedue = 0;
+        } else {
+            $assignment->timedue = make_timestamp($assignment->dueyear, $assignment->duemonth, 
+                                                  $assignment->dueday, $assignment->duehour, 
+                                                  $assignment->dueminute);
+        }
+        if (empty($assignment->availableenable)) {
+            $assignment->timeavailable = 0;
+            $assignment->preventlate = 0;
+        } else {
+            $assignment->timeavailable = make_timestamp($assignment->availableyear, $assignment->availablemonth, 
+                                                        $assignment->availableday, $assignment->availablehour, 
+                                                        $assignment->availableminute);
+        }
 
-        return insert_record("assignment", $assignment);
+        return insert_record('assignment', $assignment);
     }
 
     function delete_instance($assignment) {
@@ -347,14 +356,25 @@ class assignment_base {
         // of the new instance.
 
         $assignment->timemodified = time();
-        $assignment->timedue = make_timestamp($assignment->dueyear, $assignment->duemonth, 
-                                              $assignment->dueday, $assignment->duehour, 
-                                              $assignment->dueminute);
-        $assignment->timeavailable = make_timestamp($assignment->availableyear, $assignment->availablemonth, 
-                                                    $assignment->availableday, $assignment->availablehour, 
-                                                    $assignment->availableminute);
+        $assignment->timemodified = time();
+        if (empty($assignment->dueenable)) {
+            $assignment->timedue = 0;
+        } else {
+            $assignment->timedue = make_timestamp($assignment->dueyear, $assignment->duemonth, 
+                                                  $assignment->dueday, $assignment->duehour, 
+                                                  $assignment->dueminute);
+        }
+        if (empty($assignment->availableenable)) {
+            $assignment->timeavailable = 0;
+            $assignment->preventlate = 0;
+        } else {
+            $assignment->timeavailable = make_timestamp($assignment->availableyear, $assignment->availablemonth, 
+                                                        $assignment->availableday, $assignment->availablehour, 
+                                                        $assignment->availableminute);
+        }
+
         $assignment->id = $assignment->instance;
-        return update_record("assignment", $assignment);
+        return update_record('assignment', $assignment);
     }
 
 
diff --git a/mod/assignment/mod.html b/mod/assignment/mod.html
index d89054f301b..f957d7030db 100644
--- a/mod/assignment/mod.html
+++ b/mod/assignment/mod.html
@@ -25,6 +25,9 @@
     if (!isset($form->timeavailable)) {
         $form->timeavailable = time();
     }
+    if (!isset($form->preventlate)) {
+        $form->preventlate = 0;
+    }
     if (!isset($form->grade)) {
         $form->grade = 100;
     }
@@ -36,6 +39,11 @@
     }
 
 ?>
+<script type="text/javascript" language="javascript">
+    var dueitems = ['dueday','duemonth','dueyear','duehour', 'dueminute', 'preventlate'];
+    var availableitems = ['availableday','availablemonth','availableyear','availablehour', 'availableminute'];
+</script>
+
 <form name="form" method="post" action="../mod/assignment/details.php">	
 <table cellpadding="5">
 <tr valign="top">
@@ -90,20 +98,47 @@
 
 <tr valign=top>
    <td align="right"><b><?php print_string("availabledate","assignment") ?>:</b></td>
-    <td><?php
+    <td>
+        <input name="availableenable" type="checkbox" value="1" alt="<?php print_string('availabledate', 'assignment') ?>" onclick="return lockoptions('form', 'availableenable', availableitems)" <?php if ($form->timeavailable) echo 'checked="checked"' ?> />
+    <?php
            print_date_selector("availableday", "availablemonth", "availableyear", $form->timeavailable);
            echo "&nbsp;-&nbsp;";
            print_time_selector("availablehour", "availableminute", $form->timeavailable);
-    ?></td>
+    ?>
+        <input type="hidden" name="havailableday"    value="0" />
+        <input type="hidden" name="havailablemonth"  value="0" />
+        <input type="hidden" name="havailableyear"   value="0" />
+        <input type="hidden" name="havailablehour"   value="0" />
+        <input type="hidden" name="havailableminute" value="0" />
+    </td>
 </tr>
 
 <tr valign=top>
     <td align="right"><b><?php print_string("duedate", "assignment") ?>:</b></td>
-    <td><?php
+    <td>
+        <input name="dueenable" type="checkbox" value="1" alt="<?php print_string('duedate', 'assignment') ?>" onclick="return lockoptions('form', 'dueenable', dueitems)" <?php if ($form->timedue) echo 'checked="checked"' ?> />
+    <?php
            print_date_selector("dueday", "duemonth", "dueyear", $form->timedue);
            echo "&nbsp;-&nbsp;";
            print_time_selector("duehour", "dueminute", $form->timedue);
-    ?></td>
+    ?>
+        <input type="hidden" name="hdueday"    value="0" />
+        <input type="hidden" name="hduemonth"  value="0" />
+        <input type="hidden" name="hdueyear"   value="0" />
+        <input type="hidden" name="hduehour"   value="0" />
+        <input type="hidden" name="hdueminute" value="0" />
+    </td>
+</tr>
+
+<tr valign="top">
+    <td>&nbsp;</td>
+    <td><?php print_string('preventlate', 'assignment') ?>:
+    <?php 
+        $options[0] = get_string('no'); $options[1] = get_string('yes');
+        choose_from_menu($options, 'preventlate', $form->preventlate, '');
+    ?>
+    <input type="hidden" name="hpreventlate" value="0" />
+    </td>
 </tr>
 
 <tr valign="top">
@@ -115,8 +150,8 @@
     <td>
     <?php
        $ASSIGNMENT_TYPES = assignment_types();
-       choose_from_menu($ASSIGNMENT_TYPES, "assignmenttype", $form->assignmenttype, "");
-       helpbutton("assignment/types", get_string("assignmenttype", "assignment"), "moodle");
+       choose_from_menu($ASSIGNMENT_TYPES, 'assignmenttype', $form->assignmenttype, '');
+       helpbutton('assignment/types', get_string('assignmenttype', 'assignment'), 'moodle');
     ?>
     </td>
 </tr>
@@ -125,6 +160,14 @@
 <br />
 <center>
 <!-- <input type="hidden" name=grade      value="<?php p($form->grade) ?>" /> -->
+<input type="hidden" name="resubmit"        value="<?php p($form->resubmit) ?>" />
+<input type="hidden" name="emailteachers"   value="<?php p($form->emailteachers) ?>" />
+<input type="hidden" name="maxbytes"        value="<?php p($form->maxbytes) ?>" />
+<input type="hidden" name="var1"        value="<?php p($form->var1) ?>" />
+<input type="hidden" name="var2"        value="<?php p($form->var2) ?>" />
+<input type="hidden" name="var3"        value="<?php p($form->var3) ?>" />
+<input type="hidden" name="var4"        value="<?php p($form->var4) ?>" />
+<input type="hidden" name="var5"        value="<?php p($form->var5) ?>" />
 <input type="hidden" name="course"       value="<?php p($form->course) ?>" />
 <input type="hidden" name="coursemodule" value="<?php p($form->coursemodule) ?>" />
 <input type="hidden" name="section"      value="<?php p($form->section) ?>" />
@@ -133,6 +176,14 @@
 <input type="hidden" name="instance"   value="<?php p($form->instance) ?>" />
 <input type="hidden" name="mode"       value="<?php p($form->mode) ?>" />
 <input type="submit" value="<?php print_string('next') ?> &raquo;" />
-<input type="submit" name=cancel value="<?php print_string('cancel') ?>" />
+<input type="submit" name="cancel" value="<?php print_string('cancel') ?>" />
 </center>
 </form>
+
+<script type="text/javascript">
+<?php 
+    if (!$form->timedue) echo "lockoptions('form','dueenable', dueitems);";
+    if (!$form->timeavailable) echo "lockoptions('form','availableenable', availableitems);";
+?>
+</script>
+
diff --git a/mod/assignment/type/common.html b/mod/assignment/type/common.html
index e0ba22c4db1..045621c27fb 100644
--- a/mod/assignment/type/common.html
+++ b/mod/assignment/type/common.html
@@ -14,13 +14,28 @@
 <input type="hidden" name="description"     value="<?php p($form->description) ?>" />
 <input type="hidden" name="format"          value="<?php p($form->format) ?>" />
 <input type="hidden" name="assignmenttype"  value="<?php p($form->assignmenttype) ?>" />
+<input type="hidden" name="resubmit"        value="<?php p($form->resubmit) ?>" />
+<input type="hidden" name="emailteachers"   value="<?php p($form->emailteachers) ?>" />
+<input type="hidden" name="maxbytes"        value="<?php p($form->maxbytes) ?>" />
+
+<input type="hidden" name="var1"        value="<?php p($form->var1) ?>" />
+<input type="hidden" name="var2"        value="<?php p($form->var2) ?>" />
+<input type="hidden" name="var3"        value="<?php p($form->var3) ?>" />
+<input type="hidden" name="var4"        value="<?php p($form->var4) ?>" />
+<input type="hidden" name="var5"        value="<?php p($form->var5) ?>" />
+
+<input type="hidden" name="availableenable" value="<?php p($form->availableenable) ?>" />
 <input type="hidden" name="availableday"    value="<?php p($form->availableday) ?>" />
 <input type="hidden" name="availablemonth"  value="<?php p($form->availablemonth) ?>" />
 <input type="hidden" name="availableyear"   value="<?php p($form->availableyear) ?>" />
 <input type="hidden" name="availablehour"   value="<?php p($form->availablehour) ?>" />
 <input type="hidden" name="availableminute" value="<?php p($form->availableminute) ?>" />
+
+<input type="hidden" name="dueenable"       value="<?php p($form->dueenable) ?>" />
 <input type="hidden" name="dueday"          value="<?php p($form->dueday) ?>" />
 <input type="hidden" name="duemonth"        value="<?php p($form->duemonth) ?>" />
 <input type="hidden" name="dueyear"         value="<?php p($form->dueyear) ?>" />
 <input type="hidden" name="duehour"         value="<?php p($form->duehour) ?>" />
 <input type="hidden" name="dueminute"       value="<?php p($form->dueminute) ?>" />
+
+<input type="hidden" name="preventlate"     value="<?php p($form->preventlate) ?>" />
diff --git a/mod/assignment/type/uploadsingle/assignment.class.php b/mod/assignment/type/uploadsingle/assignment.class.php
index 153b71158e9..326b10e914e 100644
--- a/mod/assignment/type/uploadsingle/assignment.class.php
+++ b/mod/assignment/type/uploadsingle/assignment.class.php
@@ -59,41 +59,45 @@ class assignment_uploadsingle extends assignment_base {
 
         $this->view_header(get_string('upload'));
 
-        if ($submission = $this->get_submission($USER->id)) {
-            if ($submission->grade and !$this->assignment->resubmit) {
-                notify(get_string('alreadygraded', 'assignment'));
-            }
-        }
-
-        $dir = $this->file_area_name($USER->id);
-
-        require_once($CFG->dirroot.'/lib/uploadlib.php');
-        $um = new upload_manager('newfile',true,false,$course,false,$this->assignment->maxbytes);
-        if ($um->process_file_uploads($dir)) {
-            $newfile_name = $um->get_new_filename();
-            if ($submission) {
-                $submission->timemodified = time();
-                $submission->numfiles     = 1;
-                $submission->comment = addslashes($submission->comment);
-                if (update_record("assignment_submissions", $submission)) {
-                    $this->email_teachers($submission);
-                    print_heading(get_string('uploadedfile'));
-                } else {
-                    notify(get_string("uploadfailnoupdate", "assignment"));
+        if (!$this->isopen()) {
+            notify(get_string("uploadfailnoupdate", "assignment"));
+        } else {
+            if ($submission = $this->get_submission($USER->id)) {
+                if ($submission->grade and !$this->assignment->resubmit) {
+                    notify(get_string('alreadygraded', 'assignment'));
                 }
-            } else {
-                $newsubmission->assignment   = $this->assignment->id;
-                $newsubmission->userid       = $USER->id;
-                $newsubmission->timecreated  = time();
-                $newsubmission->timemodified = time();
-                $newsubmission->numfiles     = 1;
-                if (insert_record('assignment_submissions', $newsubmission)) {
-                    add_to_log($this->course->id, 'assignment', 'upload', 
-                               'view.php?a='.$this->assignment->id, $this->assignment->id, $this->cm->id);
-                    $this->email_teachers($newsubmission);
-                    print_heading(get_string('uploadedfile'));
+            }
+
+            $dir = $this->file_area_name($USER->id);
+
+            require_once($CFG->dirroot.'/lib/uploadlib.php');
+            $um = new upload_manager('newfile',true,false,$course,false,$this->assignment->maxbytes);
+            if ($um->process_file_uploads($dir)) {
+                $newfile_name = $um->get_new_filename();
+                if ($submission) {
+                    $submission->timemodified = time();
+                    $submission->numfiles     = 1;
+                    $submission->comment = addslashes($submission->comment);
+                    if (update_record("assignment_submissions", $submission)) {
+                        $this->email_teachers($submission);
+                        print_heading(get_string('uploadedfile'));
+                    } else {
+                        notify(get_string("uploadfailnoupdate", "assignment"));
+                    }
                 } else {
-                    notify(get_string("uploadnotregistered", "assignment", $newfile_name) );
+                    $newsubmission->assignment   = $this->assignment->id;
+                    $newsubmission->userid       = $USER->id;
+                    $newsubmission->timecreated  = time();
+                    $newsubmission->timemodified = time();
+                    $newsubmission->numfiles     = 1;
+                    if (insert_record('assignment_submissions', $newsubmission)) {
+                        add_to_log($this->course->id, 'assignment', 'upload', 
+                                'view.php?a='.$this->assignment->id, $this->assignment->id, $this->cm->id);
+                        $this->email_teachers($newsubmission);
+                        print_heading(get_string('uploadedfile'));
+                    } else {
+                        notify(get_string("uploadnotregistered", "assignment", $newfile_name) );
+                    }
                 }
             }
         }
diff --git a/mod/assignment/type/uploadsingle/mod.html b/mod/assignment/type/uploadsingle/mod.html
index 706575e80f6..6e583603d85 100644
--- a/mod/assignment/type/uploadsingle/mod.html
+++ b/mod/assignment/type/uploadsingle/mod.html
@@ -1,6 +1,6 @@
 <?php
     if (empty($form->resubmit)) {
-        $form->resubmit = '';
+        $form->resubmit = 0;
     }
     if (empty($form->maxbytes)) {
         $form->maxbytes = $CFG->assignment_maxbytes;