Erratic computer behavior, getting annoying

[Tanked]

The machine was running perfectly until a few days ago, when I did a registry edit to set CPU priorities (supposidly to speed up applications), and then I installed the United Devices "Think" Agent for finding the cure for cancer. It was running good for a good 3 hours or so, then I go to change the screensaver and the computer stutters a bit, then I get that damned BSOD, saying "Failure to write to drive C: data in drive C: may be lost." Everything was screwed, and I had to reboot.
When I rebooted, I got the familiar message, "System disk or disk error: Please insert a system disk and press any key". I loaded up a Windows 95 boot disk and checked the contents of the C: Drive - Everything seemed normal, except that IO.SYS was missing. I replaced it with a version from the floppy, and then the computer booted fine.
After I got into Windows, I did a remote virus scan from a different computer through my network, and it checked out clean. I also went into the registry and deleted the priority keys I had added. I fired up the "Think" Agent again, and I tried to recreated the symptoms by setting the screensaver, but everything was fine. I leave the room, and when I return a few minutes later, I get the exact same error. I reboot again.
This time, not only does it not boot, but I can't even read the C: Drive. This seemed odd, because the BIOS still detected it. I powered off my machine, and checked the cabling. Everything seemed okay.
I powered up again, and it worked...and it hasn't crashed yet.

Sorry for the long story, but what could be causing this? Hard disk? Motherboard? Software? I have the same "Think" agent running on 2 other computers, the one i'm writing this on and a 486 machine. Neither have had problems.
Here are the system specs:

AMD K6-III+ 550
Gigabyte GA-5AX Rev 4.1
256 MB Crucial PC133
GeForce DDR 32 MB
IBM Deskstar 60GXP 40 GB
Soundblaster 128, Realtek 10/100

Thanks...

 

[XeonTux]

grab and run IBM's HDD diagnostics for starters

 

[CrackRabbit]

XeonTux is right get those diagnosics and back up all your data ASAP, and be prepared to send that HDD back to IBM

 

[Tanked]

I am running the advanced diagnostics now, the quick one passed okay.
Could something like this be caused by the motherboard or overheating? The case only has one fan.

 

[Duvie]

Overheating could be the issue with the gxp 60's....


I would run the thorough diagnostic test to be sure....

YOu are not ocing any or tweaking the memory timings too much, are you?

 

[Tanked]

No, I have the memory set on Fast, CL2, but the board is only running at 100 MHz, and I have PC133 CL2 Crucial memory. Hopefully that's not the problem.
IBM's utility says my drive is okay...I was actually hoping it would find the error so I could get a new one.

 

[Duvie]

Sounds like you need to do a fresh reformat and reinstall and see if this is a software issue...Hardware appears to check out...

 

[Dufusyte]

Dude, the registry editing messed up the computer.

The first time it BSOD'd it may have written something funky ot the HD, thus corurpting the HD.

After you un-edited the registry, the registry should no longer be a problem, but the HD may still have been corrupted (see above).

I doubt this is a "hardware" problem with the HD, since it happened immediately after the registry edit.

I suggest doing a thorough surface scan of the HD.

If you have another HD around, copy everything to the new drive, reformat the corrupt drive, and then copy everything back.

Or you can just nuke the corrupt HD and reinstall everything. That is the brute force way, but it will work if all else fails. I doubt the HD hardware is at fault.

 

[Tanked]

Thanks for the input, guys. I'm doing a surface scan right now, and I 'RegCleaned' the registry. Luckily there isn't much important information on that machine, so if I still get errors, I can just cleansweep it and try again.

 

[sandorski]

Try booting into DOS from a floppy. On the floppy make sure you have FDisk. Then run FDisk /mbr, this will repair your master boot record, which may be fracked.