I am totally at a loss. This problem has been ongoing for a year now... it left for awhile, and now it is back in full force. I have no idea what is causing it. I'm hopefully going to be replacing this computer soon, but I still want to know what's causing this just because it's going to drive me crazy forever.
The computer is about 4 years old.
1ghz Celeron processor
i440BX motherboard with Creative SBLive! platinum 5.1 on board (Blaster PC kit)
512 SD RAM, 3 strips, 2 128, 1 256. One of the 128 strips is 100, the other two are 133, but they have been like that since the computer was built and this problem is only from the last year.
Two hard drives, one for Windows, one for other stuff, which have been changed in the middle of the problem with no difference.
Radeon 9000, the problem started with a Radeon 7500. Drivers have been changed with no difference.
The computer just randomly locks up. When using a browser, typing in any word processor, watching video files, audio files, or just sitting on the desktop. It's locked up in several smaller programs as well. But never ever in a game. Not once. I actually started leaving it on overnight on game title screens to see if it would lock up, and it never did. Now I do that if I need it to stay on overnight. I don't think it has ever locked up while using Adobe Photoshop either (thank god), but it locks up quite merrily when using word processors and I've completely given up trying to write anything on the computer.
I originally formatted the drive (twice, actually) with no change to the lockups. I ran the computer on each stick of RAM seperately and it locked up on each one, in different slots each time. Memtest also didn't find anything. I've unplugged every unneeded peripheral and had it running on the bare minimum, and it locked up.
I opened the case and blew a fan into it, to negate any overheating. It locked up. (paradoxically, the locking up became less frequent during the summer, when it was like 110 degrees in here...)
The video card was replaced at this point... I hoped that would be the problem, maybe. lockups continued. New drivers... lockups continued.
Then I had a SMART error come up on my C drive (a Fujitsu piece of crap), "Power On Hours Count" was failing. I thought this had to be the problem, my games are stored on D, so that's why it only locked up in Windows! It seemed to make sense... The drive failed a few months later, and I moved my D drive up to my C drive to house Windows, and got a different drive for D. My new C drive is also a Fujitsu, and my D drive is now a Maxtor. There were no SMART errors on either of these drives, and the computer continued to merrily lock up whenever it would annoy me the most. But never in a game. I also tried running a game off of the C drive. It did not lock up. It locked up while running some other program off of D as well... so there went that theory.
I tried cleaning it out, thinking maybe it was dust. That didn't help. During one cleaning session, my CPU cooler fan and heatsink FELL OFF. It had crappy plastic clips and one just snapped off before we ever touched it. Aha, I think. Maybe the fan wasn't seated properly due to a weak clip! We buy a new fan. The locking up STOPS. Hooray! That must have been the problem!
Until a month later when it starts again. I messed around with it a lot, cleaning, unhooking, rehooking things. I couldn't get it to stop again.
A few months later, I realized it hadn't done it in a couple of weeks. It continued to behave until about two weeks ago, and now it's locking up several times per hour, unless I'm in a game.
I now have a SMART error on my C drive (the fujitsu). Power On Hours Count again. From what I can tell, this error doesn't really mean much... mostly just that the drive is old and on it's way to the end of it's projected lifespan. Both Fujitsu drives were about the same age when they started giving this error, but I wonder if it could be related at all to the lockups. Unfortunately, this board is so old that it won't accept anything bigger than 30gb. I don't want to spend money on a new hard drive when I'm hopefully going to be getting an updated computer soon, and can get a good drive for probably the same amount. None of the other hard drives we have are accepted by this motherboard so I can't test it on them.
The only other thing I can think of is that the motherboard or CPU are on their way out. I don't understand why it would stop and then start again though.
Also, I've tried leaving it with a game running but minimized. The computer locked. The game has to be in focus to prevent the lockup.