Banned in first match?

I was playing my first match and had to alt-tab to close firefox, and when I came back to my game it had frozen and was not doing anything. I attempted to alt-tab back and found my game frozen with no sound, I attempted to open task manager and force close the program but it wouldn't display any windows over top the frozen game. I could alt-tab around and see they were open but I couldnt actually access these other windows. After attempting to alt-f4 and force close the program for a few minutes, I decided to shut down my pc. As it was shutting down a dialoug box appeared saying something similar to "Game Security Error Detected". Now I get kicked from servers immediately after joining. Any help would be appreciated with this. Thanks.

Basic rundown:

The error message appears when you do exactly what you did, shut down the system before the game is closed. That's just a result of your initial issue and will not affect your account.

Should it not work after restart, follow instructions posted by user "Kraeyq" above.