** SOLVED **
I don't really know what exactly fixed this problem, but by copying/using SetPatch (c) and NSDPatch.cfg (devs) from OS 3.9 to 3.1 cured this problem (as Roj hinted). There is something in NSDPatch that fixes the freeze. So to summarize:
(Applies to WB 3.1)
- copy c:SetPatch from OS 3.9
- copy devs:NSDPatch.cfg from OS 3.9
- reboot, launch game & enjoy :-)
Thanks Roj!
