Firefox won't run
Upgraded to FF3.5.x: initially, only problem was several extensions (Tab Mix Plus, Personal Menu) wouldn't work. Rebooted/restarted, but not only didn't help, FF itself wouldn't run (at all). Uninstalled/reinstalled both FF 3.0.x and 3.5.x, rebooted PC -- no joy. Noticed that with Task Manager open, trying to boot FF was followed by a brief (2-3 seconds) appearance of process "firefox.exe" but promptly disappeared. Running FF Safe Mode didn't work; rebooted Windows in Safe Mode, but FF still wouldn't launch. Was able to start Profile Manager, but button for New Profile didn't function.