The last few days my Firefox has been randomly freezing. It just stops loading websites. I close firefox, but can't kill the process. I've uninstalled or disabled all add-ons. The really wierd thing is that once this error happens, I can not shut down the PC. I have to hard reboot. I've always used AVG and Spybot as well as Ad-Aware. All programs are using the most up-to-date info. None of those programs have found any viruses, spyware, adware or general malware. I've uninstalled Zone Alarm, per Firefox forums. I've also uninstalled and reinstalled Firefox. I'm using Firefox 3 and Windows Vista. Any ideas.