Car CD Player wont play?

Hi, my Nissan almeria has inbuilt CD/Radio and the CD player works ok once I get it going but all I get for ages is cd error and it chucks them back out again. Any ideas what I can do, will it be ok to put a cd player cleaner in there to see if it needs cleaning? although I don't think that is the problem. All I have is a slot in the dash and the controls so changing it is going to be expensive and involve dismantling it I guess! Thanks