Mexxy

I'm having this problem during the last 2 ops (from 11 Dec to 15 Dec). Was playing fine until about 1 hour into the op. Game just crashes, no reason. Just running in formation, very few enemies. Section says I disconnect with the message "Steam ticket check failed: (null)". I try to rejoin, but the game crashes again about 1 min into gameplay, with the same disconnect message. I launch ArmA 3 from an addon launcher, but from reading here it appears that it should have no adverse effect. I have deleted PhysX3_x86.dll, verified integrity of game cache (validated steam game files), deleted the rtf files from User\Appdata\Local\Arma 3 and cleared my MPMissionsCache folder, as other people have suggested, but the problem still occurs. The only other option is to reinstall the game completely, which I will probably do tonight if I do not find any other solutions.