MC Crashes when i try to use text, only if I'm logged in.

Regardless of gamemode, if I am logged into the MC Servers, then type txt or a cmd on singleplayer or multiplayer, my MC crashes. It started off very small, and hardly noticeable, but is now making it unplayable. It has stuck with multiple versions of MC, and I have even tried deleting my minecraft library and starting from scratch again. It is only on this computer, but if I'm not connected to the internet it runs fine. Any fixes?