I just finished troubleshooting a most perplexing problem.
After lots and lots of trouble, including a corrupted Master Boot Record, I think that I have finally figured out the confusing set of problems I had after upgrading my OS to Windows XP Service Pack 2.
I was experiencing total system freezes. The computer would stop unexpectedly while doing nothing extraordinary. The mouse would freeze and the keyboard was unresponsive. Nothing worked except the reset button.
At one point the computer would not boot and displayed a message that the NT loader wasn't working. After doing a system recovery with the Win XP install CD and typing FIXMBR I was able to get my system to boot. I still wasn't out of the woods.
When I went to reboot later the system would not boot from a floppy or from the Win XP install disk.
A couple of tries later and I was able to boot into Windows XP. Go figure.
I ran Norton Antivirus, Memtest 86, and Maxtor Powermax trying to find the problem.
I found out it was not a virus, not bad RAM, and not a corrupted hard drive.
Because the last significant change that I had made to my system prior to the problem had been a "Format C" and reinstallation of Windows XP Professional and the Service Pack 2, I thought that the problem was some sort of software problem, such as improper chipset drivers, etc.
The fact that the computer refused to boot even to a floppy got me to thinking that the problem was not in the OS.
So I took a one dollar gamble and replaced the battery on my three year old motherboard.
In anticipation of a BIOS reset I had written down my BIOS settings earlier so all I had to do was install the battery, ground the jumper, and change the BIOS settings back to what works the best for me.
So far, so good. The system seems "cured".
I am keeping my fingers crossed. I think that I have solved this very perplexing problem.
Hopefully those of you who have mainboards that are three or more years old will think to replace your motherboard batteries before you encounter these kinds of problems.