I got also this kind of problem, have nvidia driver 304.79 installed and have tested few other versions, if someone has a good driver i will test if it solves the problem.
have changed motherboard and didnt help so sound driver is not the problem.
Sound cracking, can fix it by tab to win via winkeyhttp://youtu.be/39jCWAnHdcM
cant spec players
same happens to me when play. Starts with sound then palyer and enemy become invible after awhile screen turn to the blue background and have low fps, need to reconnect to fix it ...http://youtu.be/2WVfIUlt3Fo
My second problem is sometimes when i aim far i get my crosshair freezing in the sky, cant find word to discribe that sorry.http://youtu.be/vfBxVPhMifA
the problem is with SFE and XR on a Win7 64bit