The cd player in my 03 LS has been turning on and off sporadically recently. It will play fine for a while and then simply stop. the unit still receives power and I am able to change discs but still can't make the sound come on. When it isn't working the counter (time) on the CD display doesn't advance. sometimes it plays for about 10 seconds then cuts out. I have tried different CDs and also tried a CD cleaner without any success. Has anyone else had this problem? Also, is there an aftermarket CD changer that I can put in rather than spending the 400 bucks or so from the dealership? thanks