Computer locks up. Most common reasons are.....?

Factual Questions
1

I’ve been given my Grandmother’s computer to work on. It is a 750mhz Compaq (about 5-6 years old) with an 8meg video card, a modem, 64megs of ram and a 30 gig harddrive with Windows ME installed on it.
No other bells and whistles. Not much installed on it either, she uses it primarily for e-mail and rarely, if ever, surfs the internets. I seriously doubt that there is a virus on this thing, although I’ve been told that there was not an active virus scanner on this thing since it was purchased.
There is not a recovery disk for this machine, but there is a recovery partition on the HD.

The problem, according to her, is that she could not start it anymore. It froze up during the “checking for errors” part since it was abruptly shut down for some reason. Usually you can just cancel this routine and carry on, which is what I did when I got it home and it started up fine for me.
Then it froze after about 10 minutes of operation.
Tried to run recovery and put it back to square one but it said the recovery was unsuccessful, even though it seemed like it was going through all the correct steps, even the re-start and reboot worked flawlessly, then the message “recovery was unsuccessful” window came up on re-start.
Re-started in safe mode, ran for a few minutes while I checked for installed programs that might be a problem, then froze up again.
Swapped out the RAM and re-started. Ran long enough for me to run Scandisk for about 10 minutes and then froze up again.
Re-started, disabled any power management utilities I could find and then froze up.
Re-moved the modem, restarted, then froze up.
Re-placed the video card with a spare and it re-started and then froze up.
Each of the above steps was carried out in safe mode and regular startup mode.

Key Note; Sometimes the thing would not re-start, IOW, I would have to cycle the power several times before the monitor would turn on, even though you could hear the HD spin up and the processor fan come on each and every time.
All connections were triple checked.

I want to upgrade to XP but I can’t get the thing to stay up long enough to even do this. The length of time that the machine will run without freezing up is anywhere from 10 seconds to 15 minutes.

Does this sound like a possible virus attack, or more likely a motherboard/hardware issue?
And, are there any other steps I can take to troubleshoot this machine?

PS, I’m thinking of tossing a HD from one of the other computers I’ve got laying around here (Win 98 os) and seeing if one of them will do the trick, but I ran out of time this morning. That’s about the only thing I haven’t done yet to rule out a hardware issue and I think this will determine if it’s something on her HD or an HD hardware conflict.

2

Time it a few times. If it locks up exactly the same time after reboot, that’s very odd. It might be a power management glitch, where something’s shutting itself down because it thinks it hasn’t been used for 10 minutes.

3

I did find two suspicious programs installed on the machine;
One was VNC Server (what might that be for?) and the other was some e-mail scanning program (I Googled for it and it seems non-nefarious, can’t remember the name though).

4

I disabled the power management stuff, set it up for “Always On”.
Remember, random freez-up times anywhere from 10 seconds to 15 minutes.
Usually closer to the 30 second mark if anything.

5

Is the CPU fan spinning?

VNC is a remote access/control thing, BTW.

6

Yessir, with cover off the tower, I’ve been watching all the internal workings as I do this stuff. So, no heat buildup of any kind either.
Can VNC even be used with a modem?, she never leaves the computer on and un-tended.
I wanted to uninstall it (and the mailscanner) but it tends to freeze up as I negotiate these steps, even in safe mode.

7

VNC can be used with a modem, but it would be unusual.

If it’s freezing in Safe Mode, I’m inclined toward some kind of hardware problem - but with the number of different things you’ve swapped out to no avail, maybe it’s the motherboard that’s to blame.

Your plan of swapping out the hard drive for a blank one and installing Win98 should eliminate all question of software/malware issues.

8

I’d suspect a bad motherboard or power supply. One thing to look for is bad caps on the motherboard. A huge number of motherboards were manufactured with defective capacitors in recent years. The root cause was industrial espionage. A number of companies used a stolen formula to manufacture their capacitors, unaware that the formula was defective. They then sold them to many companies. These capacitors will cause the premature deterioration and death of any device they are used in.

See how to identify bad capacitors.

9

Good tip, I shall inspect when I get home.

10

This is happening to me right now, with my home computer. It starts fine, but after 15-30 minutes (sometimes longer), the computer would lock up and the hard drive activity light would be on solid until I remove the power cord and bring it down. Wait an hour or so and everything would come back up again just fine.
At first I thought it might be a virus or malware, but all scans reveal nothing.

I cleaned the cooling fins of the various heatsinks - same thing.

I finally exchanged my high-end video card with the card that was originally installed in the computer and got no lockups for the last 24 hours.

Short version for me was a faulty component on the video card. It gets hot after some time and then causes a lockup. I’m not sure that it’s possible to locate the faulty component on the card…easier to just buy a new card, I guess.

11

Well, I replaced the HD with one that had '98 on it and it still locked up. I didn’t notice anything odd about any of the capacitors but I’m still going with ‘bad motherboard’ on this one. Good thing my brother’s got the same computer at his place. Since he doesn’t use it anymore I just need to take her HD out of her machine and toss it in his and we should be good to go.

Thanks for your help on this.