I use the latest version of the game yet when I try to load an own map for a single play skirmish, when I don't have the initial ceasfire set up the game collapses. Or even worse when the initial ceasfire expires and then the game collapses. Pretty weird, isn't it?

The error is the "classical" one that I saw from others, but I doubt that this is caused due to the firewall, as I checked it already: