With the vehicle cold, hold the eject button in. Once you hear the motor whir, take your fist and give one good pounding (not too hard, not to soft) on the dashboard. You should get the offending Cd (which is too thick) to come out. Make a copy of it, and play only the copy. Repeat as needed for each slot. (With key off, push eject, then push the slot number).

Nate