The usual problem with this type of error is that there is something preventing the CD from being "read" by the laser, this could just be dirt and you could try a CD cleaner although recently I had a similar problem, which was fixed after removing the player from the dash with the removal tools, available from Halfords or any car accessory store. I removed the cover which is held on with securing screws where I found the cause was a paper label, originaly protecting the playing surface, of a new CD, this had jammed into the player and was prventing the CD from being read by the laser. Once this was removed with a pair of "bull nosed" pliers, the CD worked fine.
SOCA JOE, September 2008