Compiz can vary from one session to the next and one user to the next. The
settings are in the home folder for the user. I would try deleting the compiz
folder in the hidden folder .gconf. To view this you must change the preferences
in Nautilus to show hidden files or folders (Ctrl+H). Here is a thread with
someone trying something similar:
http://ubuntuforums.org/showthread.php?t=150493

I can't give more precise info now as I am in Fedora for awhile and don't have
Compiz or desktop effects installed.

I found this excellent resource when looking for a solution to a problem and it
may address the concernas of many people. You will want section 10. Install
Fusion Icon as shown. It will allow you to turn Compiz on and off and change the
settings easily.

http://www.futuredesktop.org/

Someone has gone to a lot of trouble. Every Ubuntu user should bookmark this
site.