Whenever a user turns editing on in Internet Explorer 8 (and 9 in some instances) a message is displayed on the screen as soon as editing is turned on and the page finishes loading. The full message is:

"Stop running this script? A script on this page is causing Internet Explorer to run slowly. If it continues to run, your computer may become unresponsive". The two options are Yes and No

Clicking either button causes Internet Explorer to freeze up for anywhere between 10 seconds and 2 minutes. Browsing with editing turned off is fine, and comparatively snappy.

Disabling AJAX site-wide makes no difference, nor does Javascript caching or loading online libraries. I saw a "fix" on the Moodle forums that pointed to http://support.microsoft.com/kb/175500 , but that simply removes the error message and makes the page freeze as before. Google Chrome and Firefox seem to be working fine

Our operating environment is:

Windows 7 Professional
Internet Explorer 8 (though this has been reported in IE9 as well)
IEPro7 enabled on some (but not all reported) machines
McAfee Enterprise Antivirus
IIS 6
PHP 5.4 (no caching extensions enabled)
MySQL 5.1

I've downloaded Firebug to attempt to log javascript calls, but am unsure as to where to place the initial JS commands so they're included on every page. Some assistance with that will help me try and pinpoint the issue further.