1 .Be sure you don’t have an unsaved theme in the personalization window. In that case delete it.
2. Save your theme if you didn’t do yet.
3. Switch to balanced power plan if you are using another plan.
4. Select Windows 7 and switch back to your theme then. Keep power options and personalization windows open.
5. Now change power plan to power saver
6. In personalization window -> window colour and and disable transparency. Click save changes. You can see that an unsaved theme has just been created and activated.
7. Select balanced power plan.
8. Activate your theme, delete the unsaved theme and close personalization window.

 

 

Thanks to Skynet3D on Social.TechNet.Microsoft