Can't open ArcMap - only via cmd

[BarbaraS]

We have ArcMap installed on a VPN machine and while my colleagues are not experiencing the same problem, this suddenly happened while opening a .mxd document:

Opening ArcMap as a program does not work either, it fails at "Loading document". Opening ArcMap via ArcCatalog fails as well. 

I tried the following:

• Renaming normal.mxt didn't work, neither did deleting the file
• Deleting the ArcMap folder via regedit had no effect either
• Now when I run the command as described here, ArcMap opens! So I am logged in as administrator to the machine and right clicking ArcMap in the start menu and run as admin does the trick.

Does anybody else have the same issue? Any more tips on how to make ArcMap understand that I AM the administrator already and don't need extra priviledges to open the program?