You are making a hack? You make norecoil, superbullets or something that patches the memory and you can't get it to working because the game crashes when you start joining a game? And you are sure that you have all done correct?
Let me tell you guys it's not you! Nexon just added their own anticheat. It scans the whole memory of cshell.dll (didn't look for others) when you are joining a game (at the loading screen). Then they make you crash.
I figured out two solutions:
1) Turn on your patches when your are INGAME (playing) and turn them off again before you enter the next game.
2) Bypass their scan. The scan function is located in cshell.dll! But it is virtualized with themida

license, so when you find the function it won't help you because you can only see some not readable code. Well I tried my luck and was able to bypass their scan. I'm not telling you how, figure it out by yourself. Isn't that hard.
So this was just to inform you people. Good luck!