Compiz fails to start

[Matthew Saltzman]

I tried starting Compiz from the Desktop Effects menu, and I just get a
pop-up saying it failed, then the desktop reverts to Metacity.

I tried from the command line ('compiz --replace') and it seems to
start, but I get no window decorations and the keyboard and mouse clicks
seem to have no effect (mouse cursor moves, but clicking does nothing;
typing does nothing, but <ctrl>-<alt>-<f2> gets me a VC, where I can
restart X).

This is stock F12, except for the binary nvidia drivers, which are from
RPMfusion.  Nouveau drivers don't let me turn on Desktop Effects.

Any suggestions for debugging?

TIA.
-- 
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs