G4 not recognizing CDs

[AJ]

Hello all...

I have a G4 dual 533.
My G4 has stopped recognizing CDs and DVDs.
The profiler and toast still see my CD drive, but when I insert a disk it
does not appear on the desktop or in any programs.
Also if I attach an external CD drive, the CDs still will not show up.

what is happening?
has this happened to anyone before?
what is the fix?

I've reinstalled system software and still not luck...


thanks in advance for any help...