Comment 14 for bug 145604

I can confirm that creating a new user fixes the problem. I have "flushed" all GNOME configuration files in my home directory and the problem has disappeared.
I guess fixing up some or most of the ~/.gconf/apps/compiz/ hierarchy would resolve the problem.

I have not tried yet Preferences / Advanced Desktop Settings (need compizconfig) / Preferences / Reset to Defaults , although I remember to have used it once in the past.