CZ-5000 DCO questions

[Andrew Puls Q-Bot Eye]

I have a casio CZ-5000; this is an old digital synth that has
functions like an analogue except it is programed through menues, not
knobs (DCO instead of VCO etc.) and I haven't used it for a couple of
months.  The other day when I fired it up, every note I played had a
gradual pitch decrease.  Does any one know why this would happen? I
made sure it wasn't the glide control or the way the DCO was
programed.  I thought the oscilators in these digital machines were
supposed to be stable. I'm hoping it isn't anything serious as I
really like this machine and don't know the first thing about fixing
anything digital. Thanks for any help.
==
Q-Bot, Andy Puls
q_bot at yahoo.com

["""]      ["""] ["""] """"""
[   ] ~~~  [ _ / [   ]   []
[  \]      [   \ [   ]   []
[___\      [___] [___]   []
_________________________________________________________
DO YOU YAHOO!?
Get your free @yahoo.com address at http://mail.yahoo.com