|You can try to return your system with a "restore point". See xp's help and support.|
Try a live cd such as puppy and boot to ram option. See if the drive works on another OS.
I suspect that Stuart is correct in that the DVD part is bad but you have to do some tests to prove.
I guess you could try to boot to a DVD also such as anyone's Vista or W7 if you know your system will boot to a DVD.
I support the 'Everybody Draw Mohammed Day'. A religion doesn't deny my freedom.