|If they're IDE optical drives, if they're on the same data cable, a problem with one faulty drive can affect the other drive even if the other drive is not faulty when connected by itself. |
Try connecting each drive by itself, and see what the symptoms are.
If they're both burner drives, you don't need two optical drives. A combo DVD burner drive can burn both CDs and DVDs. The CPU accesses drives one drive at a time, though it often accesses each drive in turn rapidly. The only time you save while burning when you have two is one can have a disk in one to be read, the other can have a disk in it to burn, and you don't have to take the time to change disks.
All optical drives, like floppy drives, have a sensor or switch that "tells" the operating system when a disk has been changed. Sometimes that malfunctions, usually after the drive has been used a lot
Also, for IDE drives, floppy drives, a single wire of the 34 or 40 or 80 wire data cable can have no connection or a poor connection and just one feature may not work. E.g. I answered a Topic not long ago where only the hard drive activity led did not work for a hard drive for two different people, and changing the IDE data cable cured the problem in both cases. The same may apply to the disk change wire.
The following also applies to floppy data cables.
It is common to un-intentionally damage IDE data cables, especially while removing them - the 80 wire ones are more likely to be damaged. What usually happens is the cable is ripped at either edge and the wires there are either damaged or severed, often right at a connector or under it's cable clamp there, where it's hard to see - if a wire is severed but it's ends are touching, the connection is intermittant, rather than being reliable.
Another common thing is for the data cable to be separated from the connector contacts a bit after you have removed a cable - there should be no gap between the data cable and the connector - if there is press the cable against the connector to eliminate the gap.
80 wire data cables are also easily damaged at either edge if the cable is sharply creased at a fold in the cable.
Try another data cable if in doubt.
Laser lenses get dirty eventually. Have you tried using a laser lens cleaning CD in the drives, at least once in a while, particularly before you burn ?
The most frequent thing that goes wrong with optical drives after they have been used a lot is the sleeve bearings in the drive's motor deteriorate to the point that the motor can no longer spin a disk at the full max speed, and eventually it can't even spin a disk at 1X.
The second most frequent thing that goes wrong with optical drives after they have been used a lot is something goes wrong with a laser or it's circuits - burner drives have at least two.
Optical drives don't last forever, and they're cheaper now than they've ever been. Replace the drive if you can't figure out what's wrong.