Garry's Mod Freezes on Listen Server Map Change

Well, I have a little problem. Actually a pretty big one. Every time I change the map on my listen server, Gmod completely freezes at “Establishing connection to server”, and will NOT do anything else. I can get quite annoying on Fretta gamemodes when there is a map vote.
Oh, and after that, I can’t start the server again, since it does the same thing.
Any help?

Anyone, please? I really need to know what the problem is!
It does sometimes give me a host_error if I disconnect, not sure if it doesn’t have anything to do with it. I would like to paste the error, but I can’t get it to pop up again.