WTF corrupted my drive

Last week my HD crashed. I think all the data is lost. It really pisses me off to lose 45GB of data. I still can't figure out exactly what happened.

System spec:
MSI K7-Master
Athlon 1Ghz AXIA @ 1.35Ghz
256MB Crucial PC2100 @ 150Mhz CAS2
45GB IBM 75GXP
Enermax 431W PS
Win2k SP2

I Just updated the BIOS to ver 1.1, then installed the VIA 4-in-1 drivers v1.31. In installed the bus master, INF, and IRQ, but not the AGP. I realise now that I only needed the bus master drivers in win2k (not the INF or IRQ). I then left for a few hours. Next time I rebooted and Windows wouldn't start. I booted into DOS with a boot disk and got into fdisk. Fdisk claimed that my main partition was a FAT12 drive now! I screwed around with the Win2k repair option on the CD to no avail. I booted back into DOS and found that my other partition on the drive was now corrupted also. I repartitioned the main partition, reformatted it and reinstalled win2k. I booted into win2k but I couldn't read the other partition. I could still read the partition in DOS, but not win2k. I got an old Win98 computer I had laying around and plugged my 45GB IBM into that and it could read the drive but there were some errors. I took out the 6GB drive and installed it in my new machine reformatted and installed Win98 started updating drivers and it also crapped out after a big driver update that included the VIA 4-in-1 drivers v1.31 among other drivers. The drive was bootable but highly corrupted. The partitions on the 45GB IBM were now so corrupted they were even unreadable in DOS. I ran a low level scan on all the drives and found nothing wrong, not even a sinlge bad sector.

I am now using a borrowed promise fastrak100 with 2 15GB IBM drives and Win98. I updated all the drivers including using the VIA 4-in-1 v1.31 and have no problems yet.

Does anyone have any ideas about what went wrong? I don't want to lose all my data again.