Create local/coop leads to instant crash

[gregjlanders]

Whenever I try to run a local coop or deployment round on PR, I instantly crash; it doesn't even get to the loading screen before, poof, instantly back to desktop with no error popup.

This is also the case for every mod I have, roflbox, sandbox, AIX, FH2, anything. For the mods, I also can't run singleplayer, the same things happens.

I have absolutely no idea what could be causing this. Oddly, I am easily able to join a multiplayer server, both coop online and deployment online without difficulty.

If anyone has any suggestions on what to check to try and solve the problem that would be appreciated. I would like to leave re-installing the game as a last option!
Thanks, Greg