1. Any time you make changes to an operating system, it's advisable to back up all the files and data on your PC.
2. Once your data is backed up, shut down your computer.

3. Hold the F8 key down while you restart the computer. At the prompt, choose to reboot in safe mode.
4. Once your desktop appears, click the 'Start' menu, and select 'Run.' This will open a command prompt. Type 'regedit' in the command prompt window to open the registry editor.
5. Just in case something goes wrong, back up the registry. In the registry editor's menu, Click 'File' and then 'Export.' Select 'All' under 'Export Range.' Save the file to a folder you can easily find.
6. Now search the editor for the 'wgalogon' folder and delete it. Close out of the registry editor.
7. Use your Windows search to find any 'wga*' files and delete these files.
8. Now reboot your computer in 'normal' mode. You should never see another WGA error message again.