Here's what I do when this happens.
I go into my Device Manager and I DELETE my IDE controller entries and all IDE disk entries, including the CD/DVD drive. Then I reboot and let the system re-discover all the hardware. That usually resets things back to their original config.
Doesn't always work, but if there are no wacky powertoys or what not installed, it usually fixes things.
Sometimes I have to re-install the motherboard chipset drivers over the top to get it working right, and once I even had to change the optical disk from SLAVE to MASTER to get it to work right (didn't want to do a fresh install - it was someone elses rig).
Hope somethin' in that little rant helps ya.