I found the course of my problem. It must be something to do with rights on the netlogon directory.
The script stopped working the day after patches where loaded by an external system handler. He says that my problem has nothing to do with his actions so he can’t help me.

If I logon with all my rights, there is nothing wrong BUT when a normal user logs on, the script doesn’t work. (a dosbox opens but the script doesn’t load)
I made a test user with all off my admin and user rights and this user can use the script. After taking away various admin rights, the script can’t be used anymore.
Does anyone know which user-rights the sysvol and/or the script directory needs, to be accessible for all users.
Nenya