I recently used ccleaner to clean all of my free space. I included the option of clearing cluster tips. Although I don't use this option all the time I have used it before with no ill effect. Once completed I rebooted my computer and discovered that the Aero theme was gone. I right clicked on the desktop to select Personalization but under the first option, Window Color and Appearance, the option for Color was missing. Under Themes the Aero theme is also missing. I did a search and discovered that all the Aero files are on my hard drive. When I selected it in the Theme option by browsing to the Aero theme it will not stay selected. I've tried a number of things to correct this. I have scanned for viruses and spyware and found nothing. I have used sfc /scannow in safe mode and some errors were corrected. Unfortunately this did not solve the problem. I've also used chkdsk with no success. Any suggestions would be greatly appreciated. I have used the Aero Theme on this computer for years so I know my hardware is capable of supporting it. I am using Windows Vista Home Premium with service pack two.