Windows 7 Update
The ComputerWorld has found the cause: Because apparently, the operating system has a kind of expiration date, which must be fixed by Microsoft. Because in the CAB file, which can be found under C: \ Windows \ SoftwareDistribution \ AuthCabs \ authcab.cab, the 3rd of December 2017 is listed as “ExpiryDate”.
Microsoft has to fix that, but here’s the rather big question of how. Although “only” this expiration date has to be corrected, which becomes difficult when Windows Update is deactivated. It is thus possible for users to manually import a hotfix, which could be a problem given the large number of Windows 7 users.
There are already several workarounds: The simplest way to outsmart the expiration date is to reset the system time, it is probably possible (but it does not work for everyone), to deactivate “Updates for Microsoft Product Search” in Windows Fix update.