iMac and the constantly ejected CDs

Reader Linda Gardner seeks a cure for a cantankerous media drive. She writes:

Lately, when I insert a CD into the drive, the computer, after a few seconds, ejects the CD. I have to insert the CD several times before it finally accepts the CD. My iMac is only a little over a year old. Why is this happening and what can I do about it?

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This could be happening for a variety of reasons. Moving from best case to worst:

Your CDs are dirty. Do your kids routinely handle the things after eating peanut butter and honey sandwiches? Take a gander at the ones that are being ejected. If they're dirty, give them a good wipe with a damp soft cloth.

Your iMac's optical drive is dirty. The inside of a computer can get really dusty. It's possible that some of that dust has made its way to the lens of your optical drive. You can pick up a lens cleaning CD (one that has tiny brushes on it) for less than $10 on Amazon or any store that handles gadgets and electronics (Radio Shack, for example).

It's confused. This isn't terribly likely, but it's worth a shot before taking the Ultimate Measure (see next bold item). Shut down your Mac. Start it up and immediately hold down Command-Option-P-R. Let the Mac chime two times and then let go of the keys. Try a CD and see what happens.

It's broken. Stuff breaks and if nothing else has worked it's likely you've got a bad drive. Apple can tell you for sure. Hopefully you've purchased AppleCare for your iMac, thus making this repair/replacement "free."