Try removing your 'dw' folder in your MW3 game directory. (To play it safe, back up the folder; just in case). If that doesn't fix the problem, just try restarting your game. Or disconnect from your internet network and then reconnect.
For a last thing, you might even try rebooting your PC and then try connecting again, as it's a problem on the client side (a bug in Teknogods, the developers are working on a fix-update).
Let us know if your problem still persists and we'll try to help your further
You could try removing your call sign (title) and your clantag (if you have one) in the TeknoMW3 launcher. Once you did, close the launcher and start it up again. Then start the game and try connecting to our servers again