Game unresponsive when there are more than 3 players present

[Hellen]

I host a Hamachi server for my 3 friends and I to play on, and recently I've run into a problem where my game goes unresponsive when there is more than 3 players, including me (Although everything is running fine; no lag). I can look around, but I can't move or do anything, not even access the menu or console. When the third person leaves, everything goes back to normal.

Anyone know the cause?

[Hellen]

Shameless bump.

[Killervalon]

instead of running a listen server, try running it dedicated. (and yes, you can still do it on the same computer if you're in doubt)