aiwa DX-C100M Error message?

I bought my unit in Jan 96 and have had no problems until now. I'm continually getting the message "ERROR". I'm able to clear it, and it ejects a CD, and then I can play another CD. When it finishes playing, the problem occurs again, with the unit trying, and trying to put the CD back in its slot, but eventually ejecting it, and displaying the "ERROR" message again. I've tried calling the 800 number in the manual, but it is always busy. Any thoughts or suggestions?