I had the same problem with agp440.sys on a system that I sold to a friend. Wound up being a HDD S.M.A.R.T. Problem, I had to RMA the HDD. The HDD was a Western Digital 100 Gig drive.

I could run anything I wanted by booting from the floppy with Win 98 boot disk. I trouble shot the problem for about 2 hours and then it started coming up with the S.M.A.R.T. error.