What happens:

Unity.exe cannot boot in a particular environment.

Details:

When Unity.exe runs, it creates or accesses the Roaming folder like
C:\Users\USER_NAME\AppData\Roaming\Unity
but it cannot be accessed in some environment.

Using Active Directory and folder redirection, that Roaming folder path comes to UNC like
\\fileserver\s\users\USER_NAME\AppData\Roaming\Unity
so that the cmd.exe (bat file) can never access it while booting Unity.exe.

This may happen mostly educational facilities.