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**Problem solved by myself** . Reinstalling GameGuru Classic and GG Max did not solve the problem.
Only the reinstallation of the Nvidia graphics driver 526.47 solved the problem ad acta.
With automatic installation via GeForce Experience, the Nvidia driver is apparently not always installed correctly.
Intel i7 6700K Asus Z270G , Inno3D RTX 3060 Ti, 32GB RAM 3600 MHz, 1 TB Samsung M.2 SSD. 64 Bit Windows 7/8.1/10/11.