1) Open Windows Update and click the Installed Updates link at the bottom left. If that link isn’t there, click “View update history” on the upper left, then the “Installed Updates” link in the top section.
Scroll the list down until you get to the Microsoft Windows section. Look through the updates in that section for “Update for Windows 7 for x86-based Systems (KB971033)” or “for x64-based Systems” for Win7 64-bit editions.
Click it, then click the Uninstall button at the top, then click Yes to confirm the uninstall, and close the Installed Updates window.
2) Open the Registry Editor by typing “regedit.exe” (without quotes) into the search bar on the Start Menu, then right-click it and click “Run as Administrator.”
Navigate to HKEY_LOCAL_MACHINE / Software / Microsoft / Windows / CurrentVersion / Setup / OOBE and find the MediaBootInstall item on the right.
If its value is 0, you can close the Registry Editor. If not double-click MediaBootInstall and change the value to 0, click OK, then close the Registry Editor.
3) Open a command prompt by typing “cmd.exe” (without quotes) into the search bar on the Start Menu, then right-click it and click “Run as Administrator.”
Type “slmgr /rearm” (without quotes) and press Enter.
Wait several seconds until you see a window confirming that the command was executed, then reboot your computer.
Finished !! Go to System Properties (right-click Computer and click Properties) and it should say that Windows is activated.
If not, use one of the loader programs, which should be successful. Search & Download: Windows Loader v2.1 by Daz
KB971033 should be hidden in Windows Updates to prevent it from being installed again and having the problem happen all over again. To do that:
Open Windows Update. If there are no available updates, click “Check for updates.”
Click “[x] important update[s] is[/are] available” and find “Update for Windows 7 for x86/x64-based Systems (KB971033).”
Right-click it and click “Hide update,” then click OK.
Close Windows Updates.
Hope this help !