A complete format and fresh install of Windows, Worldbuilder launched. I made a map, placed locations, calculated voronoi for territories, and it saved correctly.
A bit of an overkill measure, but I'm glad it's solved in my case. Hopefully a fix will be found that can save people this trouble.
Well I did the same, and it did NOT work up to that point where I had the same settings as before.
BUT I got it to work
after installing like 140 Win Updates regarding .Net Framework (all versions). I usually dun update my PC with Win Updates because M$ has / had a problem that they patch 1 issue and bring 2 new ones in with it...
I can now also extract with the Archives.exe which crashed too...
But after that I got it running so far. I check out later if i can save / edit etc.
Maybe you should check your Win 7 too for .Net Framework Updates.
Hopefully it works then without a complete reinstall of WindoZe.
Info: I have my Steam Folder on D:\ not on C:\ where my System is located.
So if you still "want" to do a fresh install, you don't need to reload your whole games and other stuff, because it worked without.
Seems like it was no CoH2-File related problem here, but Windows related.