I have the "premium stereo" in my 04 Z24.  It seems to have a hard time reading some disks.  When I put a CD in it will just spit it back out and say check CD.  Not all the time, just sometimes.  Also it just randomly skips, or skips tracks.  I think it's probably just dirty, but I don't know.
Does anybody know what I can do to fix it?
 
Stick the straw of a can of computer duster into the slot, pull the trigger, and move the straw back and forth. I wouldn't use a cd with the little lens brush, its liable to pick up grease from the eject mechanism.
 
 
ok, I'll try that.  thanks