Problems with Firefox 3 portable (update related?)

I'm hoping that someone here can help me. I've been using Firefox 3 Portable at work. Recently the automatic update triggered, and firefox tried to update. The update failed, and firefox crashed. When I tried to reopen firefox, I get the splash screen, and then the crash message pops up. It does this everytime.

I tried to deleting Firefox off of my flash drive and reinstalling it, and it didn't work. I then tried downloading the actual full version of firefox three on to my computer at work, and it didn't work either. I've tried uninstalling/reinstalling, using revo uninstaller to uninstall all associated files/registry values, and going through the registry manually to find anything that's causing it to crash. I'm flat stumped. Firefox 2 works fine, and I can use firefox 3 on the same flash drive on another computer. What is it that I'm missing?