Error where I can't type in chat and lag+beeping when moving

[nile (DayZ) 0]

Using the beta patch and 1.7.1.0 mod.

Occasionally during a game it will start acting like network lag, and it will beep every time i press a key on my keyboard. When I open chat it will either not let me type anything, or will type in big blank spaces.

Has anyone else encountered this?

[nile (DayZ) 0]

Now using the latest (beta build 93965, dayz 1.7.1.5):

Same problem except I've realised that it's only for the letter keys, I can move around fine using the arrow keys, but if I use WSAD or try to type anything it gets laggy and beeps.