cd changer kaput

[Paul Moore <pdm@odetics.com>]

My factory installed cd changer refuses to play any CDs
and I'm looking for any obvious things to check before
getting someone who wants $$$ involved.  I came back
from lunch yesterday and it was playing a cd fine when
I shut the car off.  When I got in the car to go home last
night the head unit showed "ER6" and then proceeded
to try each of the 6 discs and each time came up with
the "ER6."  Nothing had changed in the car, the magazine,
the cd's,etc between when it worked at lunch and when
it stopped working after.

I blew some compressed air through the unit today and
didn't get any better results (it hasn't rained in months
and this place is a dust bowl).  Looking in the installation
instructions I saw there's a horizontal/vertical switch.
Could this have jumped on its own?

Any insight or suggestions appreciated.

paul