Dedicated server won't send mission files

Most of the time when voting a mission, the server will crash after sending a few KB of the mission. This doesn't happen 100% of the time, though. It seems to send them fine if the mission is loaded by default. Logging in as admin and then changing the mission still crashed the server after sending 2KB out of the mission file. When I already have the mission (but another player doesn't), I get a "receiving mission data" while it sends the mission to the other player and gets stuck at 11KB. After this happens the server usually stops appearing on the server list.

We have tried it both with having "class missions {};" as well as having actually missions in there. In fact, when we don't have any missions there sometimes the server will not let anyone vote on missions (will show the "waiting for host" screen as if we're waiting for an admin to pick a mission even though there is no admin), though this gets fixed if everyone leave the server. Having missions defined in the class missions will allow voting but will again give the above issue.

Any help would be much appreciated. We're totally clueless what the issue is. Kellys-heroes guide did not solve the issues, and neither did the wiki.

Server runs on a xeon quad core and win2008 server.

If you want you can look up the server with "art-of-game" in your name filter.

Update: Seems to crash even when it doesn't need to send a mission (but not always, only with some missions). Some missions work consistently (Berserk and a mission I made), and others fail consistently (another mission I made, as well as some armaholic downloaded ones that people have played and responded to). But it does crash during the time where you would normally receive mission files.

Still can't solve it. Some missions work every time, some missions never work, with (virtually) nothing in common for those missions.

Missions that worked so far:

2 berzerk missions

random "thrown a few units in the editor"

Bunker control: Kabanino (pvp mission I released)

Missions that didn't work:

Domination

Clear the way (6-man coop I released)

Camp olsha

There were more that worked and didn't work but those are the ones I remember so far. Will try get a bigger list if no solution is found soon.

Still not working. Also the server sometimes does not appear on the server browser and has to be found typing in the IP.