Aloyse, Jan, I have the same problem with the IE8 machines. The 
problem is reproducible just like Aloyse said, Horde configured to 
login straight into IMP and it happens only when you close all browser 
windows and then reopen and login: a javascript error alert is 
displayed at the status bar and from then on, nothing else works. If 
you press F5 two or three times, the problem disappears.


Error details:
Windows XP SP3, same config as Aloyse's.

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; 
.NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET 
CLR 3.5.30729; FDM)

Message: 'undefined' is null or not an object
Line: 3687
Character: 13
Code: 0
URI: http://(domain)/imp/js/dimpbase.js


The line in question is a call to DM.addSubMenu. If comment that line 
out, the error happens again in other lines where there are calls to 
the same function. It's  when the script is putting together the 
quicksearch dropdown menu. "DM" is DimpCore.DMenu.

Cannot reproduce either.

There is a synchronization problem ?

I added an alert-breakpoint before this.DMenu gets initialized, see below

The error in dimpbase.js occurs before DimpCore.DMenu is defined.

--- dimpcore.js_orig        2012-11-23 10:01:16.000000000 +0100
+++ dimpcore.js        2012-11-23 10:06:17.000000000 +0100
@@ -380,8 +380,8 @@
      onDomLoad: function()
      {
          HordeCore.initHandler('click');
-
          if (typeof ContextSensitive != 'undefined') {
+alert('DimpCore.onDomLoad - breakpoint before: this.DMenu = new 
ContextSensitive()');
              this.DMenu = new ContextSensitive();
          }
      }

Same problem with dimpbase.js hanging in IE8 when imp is the first page.

our Configuration:
- WinXP SP3 with IE8 - latest
- webmail-5.0.1 on debian6 with apache2

Reproduction of the fault:
- IE8 cache must be cleared or refreshed (check for new versions... 
[x] every time i start IE )
- Horde is configured to use imp as start app ( 
$_prefs['initial_application']['value'] = 'imp'; )
1) start IE8
2) logon to horde
3) the xxx/imp/dynamic.php?page=mailbox blocks
4) hitting the Mail button in the navigation bar reloads the page
- only the very first time this happens. Afterwards loging off an on 
again is OK

Thanks a lot, but there is still other lines to comment out.
I posted the whole script.

  Hello again,
I find a solution (not perfect) but it can help users.
- comment lines containing DM.addSubMenu like this :

         if ($('horde-search')) {
             this._setQsearchText();

             DimpCore.addContextMenu({
                 elt: $('horde-search-dropdown'),
                 left: true,
                 offset: $$('#horde-search .horde-fake-input')[0],
                 type: 'qsearchopts'
             });
             DimpCore.addContextMenu({
                 elt: $('horde-search-dropdown'),
                 left: false,
                 offset: $$('#horde-search .horde-fake-input')[0],
                 type: 'qsearchopts'
             });
             /* DM.addSubMenu('ctx_qsearchopts_by', 'ctx_qsearchby'); */

             DimpCore.addPopdownButton('button_filter', 'filteropts', {
                 trigger: true
             });
             /* DM.addSubMenu('ctx_filteropts_filter', 'ctx_filter');
             DM.addSubMenu('ctx_filteropts_flag', 'ctx_flag_search');
             DM.addSubMenu('ctx_filteropts_flagnot', 'ctx_flag_search'); */

             /* Don't submit FORM. Really only needed for Opera (Bug #9730)
              * but shouldn't hurt otherwise. */
             $('horde-search-input').up('FORM').observe('submit', Event.stop);
         }

Hello,
Same problem for me. With IE 7 and IE 8 up-to-date.
Horde IMP could be adaptive with IE and not the opposite. So, anyone 
have a patch ?
Thanks

According to an other installation, the javascript dumpbase.js file 
that crashes is exactly the same.

What does your answer mean ?

Is the browser to old ?

You had stale javascript in your browser.

Everytime I login webmail, the screen keeps blank. After pressing the 
reload button on my browser the whole programm works correct.

This is the message that my browser get out.

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET 
CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)

notice: 'undefined' is Null or no object
row: 3679
sign: 13
Code: 0
URI: 
http://xxxxxxxxxxxxxxxxxxxxxx.com/Webmail/imp/js/dimpbase.js?v=f96ff7455f43a9c30f7f28e6cef94c5f