NWN2 stopped working after patch 1.22(1586)

[EDIT]
.NET 3.5 is my hero! Found a non-related post on the NWN2-server and I took the chance and installed it. To my surprise it fixed the problem. Now I'm on it again!
[/EDIT]

This is so strange. A couple of days ago I installed SOZ and everything worked fine. So I decide to upgrade now that the Hotfix for 1.23 is out (1765).

Now my game says something:
"Cant start program. Please try to re-install"

I immediately took some actions

1. Uninstalled and re-installed NWN2+MotB+SoZ from scratch. The same result
2. Installed only NWN2 and upgraded. The same result
3. Did a manual patching from NWNVault (damn boring job). The same result
4. Installed NWN2+MotB+SoZ, but no patch 1.20(1541) It works fine!
5. Did a slow upgrade patch by patch until reaching patch 1.22(1586) Again the same result
6. I undo and downgrade to 1.20(1549) and It works!

I'll go crazy! On my wifes computer. Exactly the same hardware and configuration, everything works fine. ARRRGH!
An no, going back to 1.20 is not an option. Must find solution, must find...