This is a bit of an outside shot, but... since the possibility of power blips was raised, I'll throw it out there, since I have several Abit Slot1 boards and almost all have had the same problem.
Take a look at the capacitors (green can-type things with silver tops) near the processor slot. There should be a number of them right along the back edge of the slot, and a few more in a second row right next to that. Are any of the tops bulging up? Are any of them actually split open or oozing something out of the bottom where they solder into the board?
These are the main power filtration caps for the board and if they start to go, the board may still function for a while, but will exhibit progressively wierder and wierder symptomology as either dirty power, insufficient power, or no power at all gets sent to various parts of the board and processor.
A good electronics tech can re-cap that board with good Panasonic or equivalent caps for not too terribly much (usually under $50) and it may well clear up the HDD problem and potentially even speed the machine up noticeably.
I know your machine isn't everclocked, but I just had a BX6r2 recapped and a P3-700 I had in it is now rock stable at 933, running 24/7.
Edit: A P.S. Dave, this is an Intel chipset. Doesn't use 4-in-1's,
And the latest and greatest chipset and drive controller drivers are built into Win98
Linear Mode
