completely update Windows 7, everything, SP1, all updates
restart
Go to REgedit and under currrent machine/software/windows/windows update add a 32 bit Dword called AllowOSUpgrade. Change its value to 1.
Restart.
Now navigate to C:\Windows\SoftwareDistribution\Download and delete everytthing in there. Restart.
Open command prompt as Admin and type wuauclt.exe /updatenow
Dont press enter yet
Open Widows Update and click, check updates.
Now click enter on CMD command.