For DRE to function in Windows 7, Windows Aero Glass Theme must be enabled.
Change Aero via Control Panel
- Start > Control Panel
- In the Appearance and Personalization section, click “Change the theme”
- Chose to enable Aero, select any theme under “Aero Themes”
Change Aero setting using its Windows service
Advanced users can start or stop the Desktop Window Manager Session Manager service. To do this, use the Services manager snap-in console (services.msc) or use an administrative command prompt. For the command prompt, use net stop uxsms to disable, and net start uxsms to enable Aero again.