Game crashes while I try to change game into fullscreen or go back using [Z] key

[Telemon]

So the game was running perfectly fine, until my computer was broken and I had to send it to someone, who would fix it. Now, after the renovation, Cobalt occures the same problems as Cobalt WASD was (all of which are mentioned in the title). Does anybody know how to deal with these problems? It's quite annoying when you don't want to play deathmatch anymore and want to play some plug and slam :/