Problem with QC... White picture?

I seem to be having some problems with my QuickCam of
late.  For the past few days (and this occured a couple of times
previously), I haven't been able to get a picture out of the
camera.  If I use qcam from the command-line, I get nothing but
'?' output (if I just dump to screen instead of a textfile).  Using
Xfqcam isn't any better, as I just get a pure white screen no matter
the slider setttings.

	I'm wondering if I just have a bad Qcam that I need to 
return, or if I'm doing something wrong... A reboot of the computer
nor a power cycle will cure it.  I even unplugged the darn thing
from the parallel and keyboard ports, but this doesn't even seem to
bring it back to a usable state.  As I mentioned earlier, this has
happened in the past, but I think it was luck that revived it more
than any logical explanation...

	Any clues?