Huge problem with LiteOn DVD RW DW-D22A

here’s the thing:
My drive can’t read any original (the ones you can buy in a shop) discs since I installed the new Nero. (funny thing, it can read the ones I wrote myself though).
Anyway, I’ve tried reinstalling Nero (a few times), I’ve checked all the DMA and IDE stuff, and I’m good. What’s worse the drive doesn’t even read my Windows XP disc while in the BIOS mode (which makes it so much harder to reinstall Windows - I don’t think it would help if the drive doesn’t work before windows is loaded, anyway)

Have you got any idea that might help me? I’d really appreciate even the crappiest ones.