In multiplayer, the picture freezes, then goes astray (S.T.A.L.K.E.R.: Shadow of Chernobyl)

Hello.
In a network game after 5-10 minutes of the process the picture freezes for about 10 seconds, then you receive this, and others like him:

After the folding - unfolding via Ctrl+Alt+Delete, the image is restored, the process is normally from a few seconds to a couple minutes, and then the problem is repeated many times.
This bug appears only in this game.
Video: GeForce GTS 250 512 Mb
Percent. Athlon 64 x2 3600+
RAM 3 Gb
All graphics settings reduced to low, static lighting.
Please help.