XP doesn't "see" Optical drive

An XP Pro PC SP3 with all Windows updates installed and all mobo drivers installed. Was working fine, then the DVD/RW drive no longer reads CD/DVDs. I checked device manager and it had a yellow exclamation mark on the DVD drive. I tried to update the driver and it said the driver loaded fine, but the DVD drive could not be "seen" by Windows (code 41). I swaped the SATA cable, no luck. SO..., I bought another DVD drive, figuring the existing drive had died. I installed the new drive, booted up and THIS new drive now has a yellow exclamation mark in device manager. SO... now I figure something is wrong with XP. I take out the hard drive, and put in a hard drive I had laying around with XP Pro on it. Windows comes up, and it sees the DVD drive fine, so I KNOW something in XP has become corrupted on the original hard drive. I know a complete rebuild would fix this, but I really don't want to take such a drastic step if I can avoid it. Any ideas experts???
thx, Bob R.