I had stop-errors too.
Windows XP Pro SP3 , system bought in 2008 . Problem was: the blue screen would appear and the system would shut down. In the beginning, this happened about once a day. But it started to happen more frequently. From once a day on friday, to once every half hour on sunday morning, to not being able to enter Windows at all on sunday night.
I had no clue what the problem was, and I hadn't made any changes recently, so I:
- formatted and reinstalled Windows, which seemed to be the solution at first. For hours, the system worked fine. So I started to configure everything and i thougt the problem was over. The next morning however, I was greeted again by the blue screen of death.
- stripped the pc: removed RAM except for 1 strip and changed the strips, removed all cards, removed two of the three hd's, all except the one that had the operating systems. Removed dvd drive, checked all coolers, and checked if the system worked with a linux live cd instead of win xp. In all cases, the system would work for half an hour and then it would crash, after becoming slower and slower. Note: using the linux live cd went pretty well, problems would occur only when I started moving data from one hd to another, or when I would try to acces the files on especially the hd with the operating systems. It wasn't all too clear though, sometimes it would crash when I opened the explorer.
- so I started to worry about my Asus motherboard. Replaced the CMOS battery, which had no effect. Testing took a lot of time, since the problem would occur after half an hour of sometimes hours. Bios update seemed to work, re-installed xp again, worked for a night, in the morning greeted by a blue screen agaoin, cried.
- started running tests on the disks. Hadn't done this before, because i wasn't able to burn a cd anymore due to the problem. The operating system containing HD tested defect. Had lost the receipt, but managed to get it replaced for free because the store (MyCom in the netherlands) accepted my internet banking screen dump as a receipt). The new HD works fine, in linux live the data-moving is much quicker than before and problem-free so far. Will install xp AGAIN now. Will update if problem re-occurs.
It seems the slowing down of the system, as well as the occurring of the problem more and more frequently over time should have made me realize this could be caused by a HD slowly dying. Also, I should have tested the hd's earlier and I should have run more extensive tests with linux live cd and no hd's connected. I gave up on this after two hours, but didn't conclude the problem must be in the hd's. My mind was on the motherboard too much, also because the internet was full of posts on problems with this board.
Good luck with this nasty problem. There's light at the end of the tunnel.