I'm working on a P3 machine that had two identical Win98 partitions. Both worked fine for months. Started receiving an IOS error within two weeks after an ATI video card was installed that resulted in a boot only to safe mode, a scandisk that says the partition is corrupt, and then finally no boot after post.

When the user could no longer boot, switched to the second Win98 partition. It worked for a while and then started throwing the same IOS error until finally resulting in the no boot situation as the other.

Scanning for viruses using the latest updates showed no viruses while the first partition was still booting-up. The second partition was the original for the first.

I can use a boot disk to get into DOS.
I can access FDISK and change the active partitions from one to the other, and read all info.
The drive has two additional logical partitions, which I can access and read and write to just fine from DOS.
However, even though i can read any non-hidden file from either partition, I was not able to do a SYS or to change registrys for either of the boot partitions because the partitions could not be written to. I could not unhide the registry files.
Don't know if FDISK /MBR was successful since there is no return message for that operation. No improvement after doing that.

In any case, the hard drive was removed and replaced, and WinXP was installed without a glitch. It runs perfectly, and all other hardware and peripherals work properly.

I still want to determine if the old hard drive is usable.
I have checked all the documentation from MS about IOS errors, and have narrowed the cause of this down to two possibilities: Video drivers, or a boot sector virus.
Reading the bootlog and IOS log will probably tell me more whenever I can access them.

It doesn't seem likely to be a bad disk to me, because I can write to the other partitions.
It's not likely that any of the other hardware (memory, etc) was causing this because it is all working perfectly with WinXP.

But that's not my question.
I have researched this problem extensively and cannot find a reason that explains why I can't write to either of the active partitions.

Is this just a common result of the IOS error? Or something else causing this?

Suggestions welcomed. Or should I take up Rave Dancing and abandon computers completely?