How to unprogram cd player. EE displays on screen.

I think I'm stuck in a program on my Koss home stereo 3-c.d. player that was customized by the previous owner.  It only plays the cds in slots 1 and 2, (for example).  When I try to play the one in #3, the screen says "EE" and won't play it.  It's not the cd, because they play fine in the other slots.  The problem seems to start when I hit "random". (?)  Koss Electronics no longer exists, so I can't get a manual.  Can anybody out there help?