How to lock the Windows 7 Pro desktop?

Question

Windows

On a Win7Pro machine, the SCADA system is running in full screen mode. Only the administrator has access to windowed mode. Due to security requirements, it is necessary to block access to the OS if the program is running in full screen mode. By what means can this be done?
The "Win" key is already disabled programmatically. In principle, this would be enough to solve the problem of access to the OS, but in the process of working with full screen mode, it is possible to launch other software products related to SCADA, which, in turn, involuntarily allow access to the Taskbar, which inevitably leads to access to the desktop and the entire OS.

Answer 1

security policies.
windows.microsoft.com/en-us/windows7/group-policy-...

Answer 2

You can try to change the shell, did so but for a long time.