had this same problem a litle while back. im guessing you have 2+ CD-Rom drives correct ? And you tried connecting both to the Mobo at the same time after installing Windows Xp, Correct ?... and thats when neither one of your drives were recognized by windows upon start up. The solution to this problem is simply to connect only ONE drive to the Mobo at a time, and boot up windows, It will recognize that drive, then Shut Down, and connect the second as you would normally, and boot up windows again, windows should now recognize both drive. Still dont know why this happens, but I had the same problem when Clean installing Windows XP Pro, on a new system I built.