Go into Xfire settings. Disable in-game, close Xfire and open it. Open the game then close it. Go back into Xfire settings. Enable in-game. Close and open again. Open game.
If that doesn't work you might need to reinstall both. Also, make sure you aren't running any anti-cheat programs such as X-ray.
Just out of curiosness (spelling?!), are you using a Logitech G15 keyboard? They are known to cause conflicts with Xfire in-game.