Friends even i have faced the same problem but i recovered my normal version of windows after trying this method
1)Safe Mode
• Reboot your computer and as soon as Windows logs off, start repeatively tapping the F8 Key on your keyboard.
• As soon as you see the Windows Advanced Startup options select Safe Mode within Safe Mode get yourself into these folders…
• C:\Windows\System32 (Rename wgatray.exe to wgatrayold.exe)
• C:\Windows\System32\dllcache (Rename wgatray.exe to wgatrayold.exe)
Note: Dllcache is a hidden folder, to view hidden folders do the following, go to Start, Control Panel, Folder Options,
Select the view Tab and under the Hidden Files option, select Show hidden files and folders