First see if anything on https://support.microsoft.com/en-us/help/15087/windows-genuine helps.
If no luck, contact Microsofts activation help line and explain your problem. They might give you a new license key if it's a problem with their software.
I have already been through the removal process of the Windows update KB971033, the Not Genuine message disappeared and my update screen shows this isn't installed, however, I'm now getting the message on my desktop again. Is there another update causing this?