Hi Ashton,
Usually when I have trouble with Mozilla it has to do with popups with Flash or other plugins.
Google shouldn't be doing that, of course.
Try the usual clean-up things. Empty your Mozilla caches. Delete all the temporary files in c:\\windows\\temp . Make sure your hard disk doesn't need scandisk run to clean up some problems.
Over the last week or so you've mentioned problems seeing LRPDs and Thane's picture - problems I wasn't seeing with Mozilla on Windows.
Have you changed anything else about the system recently other than the monitor?
And re your Dell monitor - a colleague had a 19" Dell trinitron that he used with his Dell laptop. It seemed to get into modes where it would flicker when the laptop said it was being driven at 75+ Hz. The monitor didn't end up in the same mode as the laptop claimed it should have been. Maybe something similar was happening to it with your friend.
Oh, and I've had very good luck buying Hitachi monitors sight unseen. :-)
Hope this helps a bit.
Cheers,
Scott.