My PC has an issue where it will turn on, get past the POST stage, but once it gets to the Windows XP loading screen, it crashes.
I've tried starting from last known good configuration, as well as in safe mode, but neither worked.
So I let it be for a few hours, and then it worked. But after a little while it reset itself and went back to its reset-once-it-gets-to-the-windowsxp-screen trick.

It was working fine recently. But yesterday I made a change and installed the yahoo/xtra bubble software, and was using IE. Now, IE started hanging on me every so often, no problem, I just killed it through task manager. But the last time it hung up, the entire PC froze also. So I reset the PC, and that's when said reset at Windows XP screen starting happeneing.

Any ideas on what's causing this? Or how I may be able to rectify it? Short of reformatting.