Buy a product called raid reconstructor from runtime.org. Load it on a beefy XP system and put a JBOD controller on it, with the 3 disks. You will need a scratch drive big enough to hold the usable data from RAID5.
The software will not touch your original data, and you can use it to build a non-RAID disk that you can then either boot (as JBOD), or use for cloning back.
The problem could be anything from a double drive failure to the BIOS getting lost, no way to know without doing lots of testing, and risking data. For all you know you have a drive failure and the other drives are on borrowed time. Since this is Win2K, then chances are these drives are long out of warranty, so it is best to spend what little time they may have left dumping to a more modern disk.
