Cold-boot vs Restart problem in Win2K

I upgraded my copy of Win NT 4 to Win 2K Professional. Ever since then, the computer boots fine from a cold-boot, but STOPS in the middle of the boot sequence when I restart (warm-boot). I’ve tried using the “/SOS” option, and don’t see anything significant except a line about not being able to identify the drive type of drive “/??/…” – but I also saw the same line when it booted normally.

My PC is a Compaq Prosignia with a P3/450 and 256mb RAM. I’ve installed SP1 & 2.

Any assistance would be appreciated.