Question....is this XP Home or Pro? Are you using SP-1 or SP-2? Is your BIOS up to date and accurate? Have you checked the state of your memory using memetest86?
I recently had something similar to this happen to my computer....it's not fun at all. Mine kept hanging on a certain file, however, and I never got a notice regarding Winlogon.exe. To fix my problem, I had to use the Windows CD to access the recovery console and then run fixboot and fixmbr...for good measure I ran chkdsk afterwards. After all of that, my machine rebooted but functioned at a reduced performance (some 80-90% less system resources). I then had to do a repair install of the OS from the Windows CD. This might fix your problem, it might not...I would check to see who else replies and whether or not they have other suggestions as there could be other problems.