Buddy having a problem & gets kicked off every single time

[Ecstasy (DayZ) 0]

So my friend has been having trouble getting on, and when he starts up a server he gets kicked off and i was in the server at the time and this is the error that popped up in the chat with his name on it.

c:\program files (x86)\steam\steamapps\common\arma 2\addons\missions.pbo

does anyone know what this is or how to fix it?

[mdms 22]

I am getting the same. Worked like 10 minutes ago, now I get kicked from all servers.

EDIT: Fixed it with Steam's "VERIFY INTEGRITY OF GAME CACHE", two of my .pbo files actually failed md5 check. Weird.

Edited July 27, 2012 by mdms