You may need to reset the receiver. Try this:
Press and hold both the ATT and SEL buttons for more than 2 seconds. This will erase your presets, but it should help the CD player behave.
If that doesn't work, you have a defective receiver. Return it for service. (& Good Luck if that's the case... :) )
Also, you can find a manual @ http://www.jvc.co.uk/files/instruction_manual/fsun3104-312.pdf
It's actually for a KD-S550, but there's not much difference.
PencilSharp!, August 2005