I am running into the same issues.
Using Firefox 3,6,3, RoboForm 6.99, WindowBlinds latest build from 2/2010 - and Spy Sweeper on a WinXP with SP3. These all do not play nice with their neighbors, but I have found this...
If you disable WindowBlinds and leave Roboform running, Firefox works.
If you disable WindowBlinds and Spy Sweeper - Firefox works.
If you disable Roboform and leave Spy Sweeper and Window Blinds running - Firefox will crash and not even open in Safe Mode.
If you leave all of them running - same result with Firefox.
If you disable Roboform and Spy Sweeper - Firefox will only work with certain skins and crash but will reopen.
I think the big culprit here is Spy Sweeper, it does cause trouble with other Windows programs as well. WindowBlinds appears to be a part of the problem, probably more with Spy Sweeper, but not all of it.
Anybody else have any ideas? I like WindowBlinds - go back to version 3 - and Firefox both - and they should work together. They did before!
A coworker of mine has this same gumbo with Windows 7 and is only having trouble with Spy Sweeper. Go figure... 