tonight I started my computer, booted into Windows 7 and logged in as I usually do. Only this time all the Aero functionality was gone. I had a read on google and it directed me to the Windows 7 Forums.
I discovered the SPTD driver for Daemon Tools Lite installed has a habit of breaking installations. So I uninstalled Daemon Tools & the SPTD driver rebooted and now everything is as it should be.