diff --git a/lib/medialib.php b/lib/medialib.php
index 78507a9482f..d59fe5777ce 100644
--- a/lib/medialib.php
+++ b/lib/medialib.php
@@ -811,7 +811,7 @@ class core_media_player_wmp extends core_media_player {
         <param name="ShowGotoBar" value="false" />
         <param name="EnableFullScreenControls" value="true" />
         <param name="uimode" value="full" />
-        <!--[if !IE]>-->
+        <!--[if !IE]><!-->
         <object data="$url" type="$mimetype" $size>
             <param name="src" value="$url" />
             <param name="controller" value="true" />
@@ -820,7 +820,7 @@ class core_media_player_wmp extends core_media_player {
             <param name="resize" value="scale" />
         <!--<![endif]-->
             $fallback
-        <!--[if !IE]>-->
+        <!--[if !IE]><!-->
         </object>
         <!--<![endif]-->
     </object>
@@ -875,7 +875,7 @@ class core_media_player_qt extends core_media_player {
         <param name="autoplay" value="false" />
         <param name="autostart" value="false" />
         <param name="scale" value="aspect" />
-        <!--[if !IE]>-->
+        <!--[if !IE]><!-->
         <object data="$url" type="$mimetype" $size>
             <param name="src" value="$url" />
             <param name="pluginurl" value="http://www.apple.com/quicktime/download/" />
@@ -886,7 +886,7 @@ class core_media_player_qt extends core_media_player {
             <param name="scale" value="aspect" />
         <!--<![endif]-->
             $fallback
-        <!--[if !IE]>-->
+        <!--[if !IE]><!-->
         </object>
         <!--<![endif]-->
     </object>
@@ -934,14 +934,14 @@ class core_media_player_rm extends core_media_player {
             data="$url" width="$width" height="$height"">
         <param name="src" value="$url" />
         <param name="controls" value="All" />
-        <!--[if !IE]>-->
+        <!--[if !IE]><!-->
         <object title="$info" type="audio/x-pn-realaudio-plugin"
                 data="$url" width="$width" height="$height">
             <param name="src" value="$url" />
             <param name="controls" value="All" />
         <!--<![endif]-->
             $fallback
-        <!--[if !IE]>-->
+        <!--[if !IE]><!-->
         </object>
         <!--<![endif]-->
   </object>
@@ -990,7 +990,7 @@ class core_media_player_swf extends core_media_player {
     <param name="base" value="." />
     <param name="allowscriptaccess" value="never" />
     <param name="allowfullscreen" value="true" />
-<!--[if !IE]>-->
+<!--[if !IE]><!-->
     <object type="application/x-shockwave-flash" data="$url" width="$width" height="$height">
       <param name="controller" value="true" />
       <param name="autoplay" value="true" />
@@ -1001,7 +1001,7 @@ class core_media_player_swf extends core_media_player {
       <param name="allowfullscreen" value="true" />
 <!--<![endif]-->
 $fallback
-<!--[if !IE]>-->
+<!--[if !IE]><!-->
     </object>
 <!--<![endif]-->
   </object>
diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 7ba916b4fb7..145952f36fc 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -7600,6 +7600,18 @@ function shorten_text($text, $ideal=30, $exact = false, $ending='...') {
                             'tag'  => core_text::strtolower($tagmatchings[1]),
                             'pos'  => core_text::strlen($truncate),
                         );
+                } else if (preg_match('/^<!--\[if\s.*?\]>$/s', $linematchings[1], $tagmatchings)) {
+                    $tagdetails[] = (object) array(
+                            'open' => true,
+                            'tag'  => core_text::strtolower('if'),
+                            'pos'  => core_text::strlen($truncate),
+                    );
+                } else if (preg_match('/^<!--<!\[endif\]-->$/s', $linematchings[1], $tagmatchings)) {
+                    $tagdetails[] = (object) array(
+                            'open' => false,
+                            'tag'  => core_text::strtolower('if'),
+                            'pos'  => core_text::strlen($truncate),
+                    );
                 }
             }
             // Add html-tag to $truncate'd text.
@@ -7685,7 +7697,11 @@ function shorten_text($text, $ideal=30, $exact = false, $ending='...') {
 
     // Close all unclosed html-tags.
     foreach ($opentags as $tag) {
-        $truncate .= '</' . $tag . '>';
+        if ($tag === 'if') {
+            $truncate .= '<!--<![endif]-->';
+        } else {
+            $truncate .= '</' . $tag . '>';
+        }
     }
 
     return $truncate;
diff --git a/lib/tests/moodlelib_test.php b/lib/tests/moodlelib_test.php
index 78b2a2d16bd..c976de32987 100644
--- a/lib/tests/moodlelib_test.php
+++ b/lib/tests/moodlelib_test.php
@@ -869,6 +869,14 @@ class core_moodlelib_testcase extends advanced_testcase {
             "tags that ...</blockquote></p></div>", shorten_text($text));
     }
 
+    public function test_shorten_text_with_tags_and_html_comment() {
+        $text = "<div class='frog'><p><blockquote><!--[if !IE]><!-->Long text with ".
+            "tags that will<!--<![endif]--> ".
+            "be chopped off but <b>should be added back again</b></blockquote></p></div>";
+        $this->assertEquals("<div class='frog'><p><blockquote><!--[if !IE]><!-->Long text with " .
+            "tags that ...<!--<![endif]--></blockquote></p></div>", shorten_text($text));
+    }
+
     public function test_shorten_text_with_entities() {
         // Remember to allow 3 chars for the final '...'.
         // ......123456789012345678901234567_____890...
diff --git a/webservice/amf/testclient/index.php b/webservice/amf/testclient/index.php
index 7d84acd7373..fbb3e714aec 100644
--- a/webservice/amf/testclient/index.php
+++ b/webservice/amf/testclient/index.php
@@ -48,14 +48,14 @@ $output = <<<OET
 <param name="base" value="." />
 <param name="allowscriptaccess" value="sameDomain" />
 <param name="FlashVars" value="rooturl=$CFG->wwwroot" />
-<!--[if !IE]>-->
+<!--[if !IE]><!-->
 <object type="application/x-shockwave-flash" data="$url" width="100%" height="1000">
   <param name="base" value="." />
   <param name="allowscriptaccess" value="sameDomain" />
   <param name="FlashVars" value="rooturl=$CFG->wwwroot" />
 <!--<![endif]-->
 <p>You need to install Flash 9.0</p>
-<!--[if !IE]>-->
+<!--[if !IE]><!-->
 </object>
 <!--<![endif]-->
 </object>