I'm trying to upgrade from Firefox 5.0.1 to 7.0.1. The upgrade installs successfully, but it won't start. It crashes everytime it opens. I can reinstall 5.0.1 and it will work. While 5.0.1 was working, I removed all the plugins, and then upgraded to 7.0.1. It still crashes when the application starts. I also went in to Add/Remove Programs through Windows Control Panel and removed Firefox completely, and even deleted the installation directory. I then tried to do a completely new install into a different installation directory, and it still crashes on startup.