I wrote a powershell script, wich modifies some Office files. I am using ninja rmm to deploy the script. It run as the system. My problem is, that I am using [System.Windows.MessageBox] which is now showing at the user side. It is needed to ask some questions and get feedback from the user, like is it okay to close all Office apps.
Peter,
Welcome to the forums.
First of all - where’s the script? 
Second: What’s the question?
Ditto what Olaf says … .and did you mean “it is NOT showing” ???