Hmmm. Complete freezing you say? I would first think of a power or heat issue. Or both. Followed by corruptions (which can be caused by unscheduled reboots from power or heat issues). For example, just recently my PC wouldn't get past the XP login screen. Well it would, but would error and not allow Explorer to run (which is the whole of what most people call "Windows" for XP - ie. the desktop). You could get Firefox though from an ALT+CTL+DEL task manager (run option).
After a while of ignoring comments from people saying it was adware
I found out it was actually one of my windows files which had corrupted. Removed the file (actually moved it just incase) after reading up on it on the web, rebooted, and it all worked fine. And Windows recreated the file, which was nice
Anyhows, turned out that I'd forgotten the PC had rebooted every now and again (I mean suddenly froze with black screen - no BSOD - and sometimes rebooted itself, or I had to manually reboot ie. keep finger on power button for a few secs) ever since I had installed a new graphics card, which on one occasion corrupted the file. Of course it was because my PSU couldn't handle all the devices on it (there is one or two), and the graphics card was the final straw (needed it's own power cable). Weedy 300w effort basically. So, I got a 650w 3 fan effort (hell, they are cheap as pants), and everything runs smoothly again. Tops.
Oh, and I used to run DBC perfectly well on a 450Mhz P2 with a GF2 card (think was 32mb or so).
Failing all that, then how long since a format and reinstall? Esp with windows 9X.
Cheers
I am 99% probably lying in bed right now... so don't blame me for crappy typing