Umm, actually, I got the problem to STOP by going back to SP1. A little history:
900MHz Athlon Jetway 663AS Mobo. 256MB PC133, ATi Xpert 98
I had W2K Pro installed on an old Maxtor 3GB ATA33 drive. It had been a little flaky lately so when on Friday night when it decided there were bad clusters I did the honorable thing and bought a new WD 30GB ATA100. I reinstalled win 2K clean, got everything up to snuff including SP2 and the latest VIA chipset drivers, then attached the old drive to the Secondary IDE controller, started up and copied data (no system files) from the old drive to a clean partition on the new drive.
Shut down, remove the old drive, reboot and WHAM! Inaccessible Boot Device. Checked boot.ini to make sure it hadn't somehow tried to point at the wrong physical drive and everything looked right. So I reformatted the partition and reinstalled, got everything up to snuff again. Shut it down, came back a few hours later and started it up- Cannot load because file XXXXXXX is missing or corrupt. This popped up within seconds of selecting to start Windows 2000 Professional.
<shame>Sorry, I didn't bother recording the exact file name</shame>
Went through various iterations of this until I decided to eschew SP2 and install SP1 instead. It was working last night. We'll see what's up when I get home tonight.