I got the same error with RC2. It seems like you didn't properly uninstall Aero Glass before you tried to install a newer version or the same version to another location. It took me a long time to figure out that the Batch file which installs AeroGlass also creates a scheduled task called "Aero Glass" which must be deleted manually with the task scheduler before installing any version of Aero Glass when you don't want to install it to exactly the same location as the first instance was installed.