OK now it works. But whenever I try to play in my map I get an access violation error. Restarting the PC doesn't help. My friends can play in it normally though.
I had the same problem just recently, and I got the exact same error message. I believe the reason is that you have too many big scenerys. I had three 1200x960ish size scenerys in a map of mine and my game did the same thing. Polyworks was still showing all of the scenery though in the map.
What I had to do was to not only take the scenery out of the map, but I had to take the scenery out of my
scenery-gfx folder as well to fix the problem. I believe that once you use a scenery in the map, even if you get rid of it, it will still register as being in the map. You need to either remove the scenery from you
scenery-gfx folder in your Soldat directory, and then rename it if you want to put it back.
Good luck. What I did worked, and it should work for you as well. Since your friends don't have the original huge scenery screwing up your game, it doesn't affect them. That's all I can say.