Client Error2_4 Zombie Mode

Moin.
I have a Problem in the 3 Zombie Maps. When I Play there and use a MG (MG3 and other), then comes so at Level 20 a Message: Client Error 2_4. I was kikked then. If i go back to Map, Message: You can´t, you have failed... ! When i changed my Gun for example to a Rifle, then comes no Error! I have installed the Client new. Doesen´t Matter. Big Prob is my bad english too, i come from Germany and if i search here a Tip for my Prob, i dont understand all Words. Have someone a Idea, what can I do?


Greetings.
(German Forum needed,hahaha)