Crashing whenever I join my server - Launching Singleplayer first fixes

So, if I join my server without joining single player first, I get “hl2.exe has stopped responding” and whatnot. It’s not just me, the same problem happens to other people on my server.

However it only happens sometimes, one day it’ll be fine the next it won’t…

Here’s the crash dump: http://dumps.garrysmod.com/?view=302863851

Any ideas?