VW phatbox "no disc" issue

[murrey1]

I recently took the DMS out of the Phatbox to change the music.  This is the original DMS that I bought at least 5 years ago (can't remember when) for my 2000 VW Jetta.  Now, after I put it back in, it will recognize the disc and start playing the first track of the first cd.  I can skip among the tracks of that cd with no problem, but when I try to change cds, the DMS stops playing and the "no disc" message pops up.  After that, nothing works unless I unplug the Phatbox and plug it back in - and then the same thing happens.  Anybody know why this is happening?  Thanks.