I play with 2 other friends and one of them has the same issue. The only correlation I can see is him and I are both on MAC computers using Bootcamp to run Windows. Maybe there is an issue with this? Arma 2 works just fine though.
I use a Retina Macbook Pro. 2.7GHZ i7, 16GB RAM, 512 SSD, Geforce 650, Bootcamped Win7 64 bit.