not installing microsoft securety essential error code ox80070643
And, verify that you have removed all other real-time antimalware products that were ever installed on your PC, including free/trial products that were installed when the PC was purchased (Norton, McAfee, TM, AVG, OneCare, Malwarebytes (paid), etc). Then, use the cleanup tools here: List of anti-malware program cleanup/uninstall tools
NOTE: If you have installed Adobe FLASH, and you already had the google toolbar, you were presented with the option to install “McAfee Security Scanner”, which is selected by default. If you were caught by this, and unknowingly/accidently installed McAfee, uninstall it and use the McAfee cleanup tool in the list above.
Verify that your PC clock is correctly set. If not, correct it.
Verify that Windows Defender is uninstalled (if XP), or Disabled (if Vista/W7).
Verify that you are up-to-date with SERVICE PACKS and updates (including .NET). Yes, it can take some time to do this.
If the problem persists, submit a support case to Microsoft: https://support.microsoftsecurityessentials.com/?scrx=1
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