Could you please tell which Intel GMA you have? Id suggest you restart the DWM. This can be achieved by restarting the DWM.exe process. Kill it and then enter DWM.exe in the new Task. Also try driver Rollback. If any of this does not work, try re-evaluating your PC again. Windows Vista is known to be buggy when it comes to evaluating hardware performance and its capabilties, an upgrade to 7 would be appreciable too.