I cannot seem to install any newer versions of FireFox on any of my
PCs. FireFox 3.0.17 and earlier works fine, but anything newer
crashes immediately upon trying to open the program.

I've tried completely uninstalling, removing all apps and add-ons,
deleting all preferences and saved Mozilla Files and Folders and doing
a completely fresh install, and I still have this same issue.

When I uninstall and go back to the earlier version, it magically
works again.

Here is a Crash Report:

BuildID: 20100115144158
CrashTime: 1264181776
FramePoisonBase: 00000000f0de0000
FramePoisonSize: 65536
InstallTime: 1264181763
ProductName: Firefox
ReleaseChannel: release
StartupTime: 1264181773
Throttleable: 1
Vendor: Mozilla
Version: 3.6

Hope you can help!