I've been running Windows 7 (32-bit, I believe) for a couple of months now. I'm sorry, but I don't know the build number or where to look for it. I was writing an e-mail in Firefox when suddenly Firefox stopped responding. After a minute I tried to run the task manager, but my computer had completely frozen. I reset the machine but when Windows 7 tried to boot it hung on the Welcome Screen. I can't get in using Safe Mode, either. It hangs on the Welcome Screen also. I booted to Windows XP on another drive (which I'm using now) to check that the computer was still functioning and that the boot HDD of Windows 7 was also. Both worked fine. I think Avast! Antivirus might have been doing a scheduled scan at the time of the crash. Here are my potentially pertinent physical computer specs: ABIT IX38 Quad GT, Intel E6850, GeForce 9600GT, 2x2GB Patriot 240-pin DDR2 1066 If there's any other information you need from me, just ask. I'll do what I can, but I'm better with computer hardware than I am with software. This kind of thing makes my head spin... Please help!