Found a fix. I'm not sure exactly what caused it, but what I did was deleted the Arma 3 Alpha folder from user\Documents\Arma 3 Alpha , also user\Documents\Arma 3 and finally user\AppData\Local\Arma 3. I was able to play without problem. Bare in mind, I only tested this once.
Update: Scrap that, it seemed to temporarily fixed the problem, but it is crashing still.