Have all devices been set correctly in bios?
Opticals as cdroms, HD's as correct size.
Can also try auto for all.
Also, you have tried many different discs, right?
Can also be IDE drivers (update to latest)
Can be ASPI (use forceaspi2 (with adaptecs 4.6 - 1021 layer, not adaptecs 4.7x layer)
Have you got any TSR programs like creative disc detector, anyDVD, windvd remote or do you have the patin couffin engine (Blindwrite suite) or any Roxio/EZCD software installed?