FWIW here's another weird one. (XP Pro, SP2, NTFS)
I have 4 on-board HDs in one of my machines:
One drive is for sytem files
One drive has applications only on it
Two drives are for various data and a few key applications.
A week or so ago the drive with only applications on it 'died' and took down the machine. On reboot I couldn't find that drive anywhere, not in Computer Management/Storage, not even using the drive manufacturer's utility from a bootable floppy. The rest of the system ran fine without that drive, except there was no longer any network access from this machine. No problems with cabling, power supply, nothing of that kind.
I decided to fix the network issue first and, as a first step, used Device Manager to delete the network adapters. A reboot found the network hardware and installed drivers for it. Voila, the network was back (they should all be so easy).
HOWEVER the missing drive was also back. A couple of days later I needed to reboot the system for something or other. The system came back up with same drive missing, and network access vanished again. Being a firm believer in trying what worked last time I deleted the network adapters and rebooted again -- and back came the network AND SO DID THE DRIVE.
I have to admit that, if anyone else reported this, my first reaction would be that they're mistaken...or nuts. So, until I can figure this out I'm living in the Twilight Zone.