Cannot use CTRL button in game.

Yesterday, everthing worked fine for me. But today, when i opened CF, i tried to crouch , but it didnt work. So i changed my crouch button to alt, and it works fine for me. but i change it back to CTRL, it doesn't work.I thought my ctrl button is broken , but when i ctrl+V and ctrl+z... everything works fine.Is this a new bug????