Having command mat_antialias updated when launching the game (via autoexec or launch options) may cause the game to crash. I did some testing and found out that it's caused by also having -dxlevel in your steam launch options. By removing the dxlevel command your game should load normally and your dxlevel value should remain unchanged. I imagine this could also work for CS:GO, but I don't play that game so I haven't tested it.