Something

/usr/bin/compiz.real (core) - Warn: SmcOpenConnection failed: Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed
/usr/bin/compiz.real (core) - Error: Screen 0 on display ":0.0" already has a window manager; try using the --replace option to replace the current window manager.
/usr/bin/compiz.real (core) - Fatal: No manageable screens found on display :0.0