Perhaps this fixes http/1.0 problem?

web/templates/default/msgs/msgs.inc

@@ -10,8 +10,8 @@
 @@JS:template.show_choice==undefined ? '' : '(' + template.show_choice + ')<br /><br />'@@
 </div>
 
-<form name="DeleteMsg" action="management.ssjs?Action=Delete" method="post">
-<input type="hidden" name="msg_sub" value="^^sub:code^^" />
+<form name="DeleteMsg" action="management.ssjs?Action=Delete&amp;msg_sub=^^sub:code^^" method="post">
+<!-- <input type="hidden" name="msg_sub" value="^^sub:code^^" /> -->
 <table class="msglist" cellpadding="5" cellspacing="2" border="0" width="100%">
 <tr class="msglist">
      @@JS:template.can_delete?'<th class="msglist"><input name="SelectAll" title="Select All Messages" type="checkbox" onclick="checkBoxes(this.form, this.checked)" /></th>':''@@
@@ -25,7 +25,7 @@
     <!-- %%JS:template.color=0%% -->
     <<REPEAT messages>>
     <tr class=@@JS:((template.color++)%2==0)?'"msglist1"':'"msglist2"';@@>
-    @@JS:template.can_delete?'<td align=center><input name="number" value="'+RepeatObj.number+'" type="checkbox"></td>':''@@
+    @@JS:template.can_delete?'<td align=center><input name="number" value="'+RepeatObj.number+'" type="checkbox" /></td>':''@@
        <td align="center">
             @@JS:if(RepeatObj.attachments>0) '<img alt="Attachment" src="/graphics/attach_black.gif" />'; else '&nbsp;';@@
        </td>