Index: assignment-tool/tool/src/webapp/js/assignments.js
===================================================================
--- assignment-tool/tool/src/webapp/js/assignments.js	(revision 312386)
+++ assignment-tool/tool/src/webapp/js/assignments.js	(working copy)
@@ -349,8 +349,8 @@
     var children = container.getElementsByTagName("div");
     
     // Show/hide the messages
+    showOrHideSelectGroupsMessage();
     if (groupRadioSelected) {
-        showOrHideSelectGroupsMessage();
         for (i = 0; i < children.length; i++) {
             if (children[i].id !== groupMsg.id) {
                 children[i].style.display = "none";
@@ -358,7 +358,6 @@
         }
     } 
     else {
-        showOrHideSelectGroupsMessage();
         for (i = 0; i < children.length; i++) {
             if (children[i].id !== groupMsg.id) {
                 children[i].style.display = "block";
@@ -382,13 +381,32 @@
         }
     }
         
+    // Get the form submission buttons
+    var btnPost = document.getElementById("post");
+    var btnSave = document.getElementById("save");
+    var btnPreview = document.getElementById("preview");
+    var buttons = [btnPost, btnPreview];
+    if (btnSave !== null) {
+        buttons.push(btnSave);
+    }
+        
     // Show/hide the groups message
     if (groupsRadio.checked && !groupsSelected) {
         groupMsg.style.display = "block";
+        
+        // Disable the post, save and preview buttons
+        for (i = 0; i < buttons.length; i++) {
+            buttons[i].disabled = true;
+        }
     } 
     else {
         groupMsg.style.display = "none";
+        
+        // Enable the post, save and preview buttons
+        for (i = 0; i < buttons.length; i++) {
+            buttons[i].disabled = false;
     }
+    }
 }
 
 function toggleGroups(clickedElement) {
Index: assignment-tool/tool/src/webapp/vm/assignment/chef_assignments_instructor_new_edit_assignment.vm
===================================================================
--- assignment-tool/tool/src/webapp/vm/assignment/chef_assignments_instructor_new_edit_assignment.vm	(revision 312386)
+++ assignment-tool/tool/src/webapp/vm/assignment/chef_assignments_instructor_new_edit_assignment.vm	(working copy)
@@ -1827,15 +1827,15 @@
 			</p>
 		</fieldset>
 			<div class="act">
-				<input accesskey ="s" type="button" class="active" name="post" value="$tlang.getString("gen.pos")" 
+				<input accesskey="s" type="button" class="active" name="post" id="post" value="$tlang.getString("gen.pos")" 
 						onclick="javascript:document.newAssignmentForm.onsubmit();showNotif('submitnotif','post','newAssignmentForm');document.getElementById('option').value='post';document.newAssignmentForm.submit();return false;" />
-				<input accesskey ="v" type="button" name="preview" value="$tlang.getString("gen.pre")" 
+				<input accesskey="v" type="button" name="preview" id="preview" value="$tlang.getString("gen.pre")" 
 						onclick="javascript:document.newAssignmentForm.onsubmit();showNotif('submitnotif','preview','newAssignmentForm');document.getElementById('option').value='preview';document.newAssignmentForm.submit();return false;" />
 				#if (!($!assignment && !$assignment.draft))
-					<input accesskey ="d" type="button" name="save" value="$tlang.getString("gen.savdra")" 
+					<input accesskey="d" type="button" name="save" id="save" value="$tlang.getString("gen.savdra")" 
 							onclick="javascript:document.newAssignmentForm.onsubmit();showNotif('submitnotif','save','newAssignmentForm');document.getElementById('option').value='save';document.newAssignmentForm.submit();return false;" />
 				#end
-				<input accesskey ="x" type="button" name="cancel" value="$tlang.getString("gen.can")" 
+				<input accesskey="x" type="button" name="cancel" id="cancel" value="$tlang.getString("gen.can")" 
 							onclick="javascript:document.newAssignmentForm.onsubmit();document.getElementById('option').value='canceledit';document.newAssignmentForm.submit();return false;" />
 				<span id="submitnotif" style="visibility:hidden">$tlang.getString("gen.proces")</span>
 			</div>