The problem arises from a conflict between RFEM or RSTAB and the mouse driver by 3Dconnexion. To solve the problem, right-click the driver using the icons in the Windows taskbar, and activate and deactivate the creation of the log file in the shortcut menu. Finally, you should be able to start RFEM 5 and RSTAB 8 again.As an alternative, you can replace the existing driver with an older driver (version 10.8.3, the download link attached). Then, you can use your Dlubal software as usual.