Bug/Issue Client crashing when placing seperator (multiplayer)

Friend of mine is playing with me via steam, we dont have any mods installed.
Every time me or him are placing down a seperator his game freezes up and closes.

[Info] UniverseClient: Joined server as client 2 [14:021.398]
[Info] detected supported OpenGL texture size 16384, using atlasNumCells 128 [14:021.398]
[Info] detected supported OpenGL texture size 16384, using atlasNumCells 128 [14:021.411]
[Info] detected supported OpenGL texture size 16384, using atlasNumCells 128 [14:021.434]
[Error] Cannot set Steam achievement kill10poptops [14:03:26.270]
[Info] Client received world stop packet, leaving: Removed [14:03:45.163]
[Info] Client received world stop packet, leaving: Removed [14:04:06.506]
[Info] Client received world stop packet, leaving: Removed

[Error] Cannot set Steam achievement kill10poptops [14:09:29.344]
[Info] Client received world stop packet, leaving: Removed [14:11:05.711]
[Info] Application: quit requested [14:11:05.711] [Info] Application: quitting... [14:11:05.711]
[Info] Application: shutdown... [14:11:05.713]
[Info] UniverseClient: Client disconnecting...

any help?