MrMayno
"enable desktop composition" is not an option.
Any default Windows 7 install should have this option available. If you don't, it's likely that the "Desktop Window Manager Session Manager" service is, for some reason, not running. SONAR relies on this service.
You can find the Windows Services tool by typing "services" in the start menu. Can you confirm that its Startup Type is set to "Automatic" and its Status is "Started"?
Thanks.