stereo error codes

Hi. I'm new to this forum and hope somebody out there can help me! I have a 1996 Oldmobile Cutlass Supreme w/ factory AM/FM/Cassett/CD. The radio works fine, it's the tape and CD player that have problems. When I can get it to work, the CD player plays just fine. After ejecting the CD, though, it won't accept a new one and I get error codes like ERR20 and ERR23... Sometimes after the car is turned off it will finally take a CD again. At first I thought that maybe it might need to be cleaned but how can you do that if it won't even accept the cleaning CD? Also, the tape player will accept a tape but won't play it and spits it right out. The two problems occurred within hours of each other. Anyone else had problems like this?? Any suggestions are GREATLY appreciated! Thank You!!