CD eject noise

Has anyone heard of or had this problem: my CD/Cassetter radio makes the sound like it's ejecting every 15-20 seconds. Does this when radio is playing or CD is playing. What should I do?

its most likely a stuck cd in the unit. Is it a multi stack unit? Be careful with burned cd's with glued on labels they can cause it to stick also. Burned cd's also are thinner than factory cd's so they can cause this noise also because they can't pick up the thinner cd's.

It still does it when there is no CD in it which is so strange. It is a single CD player.