I'm not sure what's causing this, but I can't create any games in STA2 online without the game crashing. I do have the 1.1 patch installed and it didn't make any difference. And I can't seem to join any games. I don't have any mods installed yet.
You'll likely be running either windows version 6.0 (Vista) or 6.1 (windows 7) which both share a semi new network stack. The fleet ops team have a fix for this is the guise of their unofficial 1.2 patch. It should fix your problem.
I'll try the patch, but I'm going to back up the original first.