OK, first try this and a warning - DO SO AT YOUR OWN RISK!
1. Go to Menu | System Tools | System Monitor - look for any thing running in processes that says Compiz - right-click the process and 'kill it'
2. Check up on 'Startup Applications' which should be under Menu | System Tools | Preferences - and if Compiz is showing, uncheck it.
3. Launch Synaptic Package Manager - Menu | System Tools | System Administration | Synaptic Package Manager - and in the little 'search box' near top middle and search for 'Compiz' - check all the named packages that show - right-click each one and select 'Mark for complete removal' - following this (YOU HAVE BEEN WARNED!) you may end up with a non-working installation of Zorin!