I too had this problem after upgrading to 10.10 Maverick where I blindly enabled the compiz ppa in ubuntu tweak 0.5.7 because I was after the cylinder effect when rotating the cube. I didn't realise it wasn't available for 64 bit version of 10.10 (although I had it working fine in 10.04?) so I purged the PPA via Ubuntu Tweak, uninstalled everything to do with compiz in Synaptics manager (thought they were getting rid of this in Ubuntu?) and then reinstalled all things compiz. Rebooted and all is well in UbuntuWorld again!

Thanks for the tips people!