I got a similar problem
my setup:
Epox EP-8k7a+
AMD Thunderbird 1.4@1.6
512 MB CL2 DDR Ram
a 30 gb and a 40 gb and 2 60 GB IBM drives
Geforce 3 card and so on and so forth
Installed earlier a beta of WinXP (build 2463 or something close)
(works fine with win2k driver for my onboard HPT370(a) ata 100 controller)
Got myself the devils own release of build 2600
seems it doesnt like the driver I used to install build 2463 very much ..... At this moment I'm dling a new bios update and I hope that will solve my problem ... But I suspect I have to wait until Highpoint-tech (.com) releases a WinXP driver for the HPT370(a)Controller