Is your bios up-to-date? Are there any firmware updates available for the DVDrom drive? Check the DVD's manufacturer's site and see if there are any known issues with XP.
Do you have the VIA chipset, if so, do you have the newest 4in1's installed? Also, if you have the via chipset, have you tried the mini-port drivers?
If you don't have the via chipset, check your motherboard's site and see if there are any other IDE driver updates available.
Have you tried other master/slave configurations? Like placing it on it's own IDE channel, etc?