DVD drives won't recognize DVD's.

Extreme hair-loss on this one.
Both of my DVD drives will show CD disc contents and play CD's. However, DVD's are not even recognized as present in the tray, or contents displayed in "my comp."
These drives worked fine until a trojan got through, (Guess I shouldn't have believed in the "Move to chest" solution. Ran the "Read me first" steps, which apparently the malware had much to do. XP Home was running much better, but never got the drives to recognize DVD's afterwards. The system finally became so unstable I threw in the jock and performed a clean install with all the upgrades including SP3.
The system seems to be running well but no DVD recognition, K lite installed as well. The drives aren't very old, and I find simultaneous drive failure odd. The device manager shows no warnings, all drivers updated. One other odd item: The Raid controller becomes un-installed and says there is a problem with the device until updating the driver one more time in a row. Maybe this is totally unrelated.
My talented computer buddy says, "Oh, that's a weird one", which is normal, as I own it.
Help, need my hair back!

 

Hope my reply is not redundant, as I think my first one got lost.
Thank you, Halo for your help.
The chip set is updated.
The System Tool programs indicate the PC is doing well, IE: Hardware, etc.
The device mngr. says: No conflicts, drivers up-to-date.
Downloaded Nero 8 and the MSC codec pack as well.
Still, no DVD (any type) recognition, but CD's read fine.
Could a virus blow out the DVD player firmware?