The OP in that thread had the exact same issue me. RichardG867's post fixed it for me:
1. Fire up cmd.exe 2. AT HH:MM /INTERACTIVE cmd.exe 2. (where HH:MM is your Windows time + 1 minute) 3. Wait 4. On the new prompt, enter: 4. RUNDLL32 shell32.dll,Control_RunDLL desk.cpl 5. You will be presented with desktop properties for SYSTEM user. 6. Change the theme to classic using these desktop properties.