I just made a new computer and on my old one running Vista 64 I had no such problems mind you I am using the same router setup so it should not be affecting it we have had several lans with several different computers and never had this problem. Now I am running Windows 7 64 and in the multiplayer (was playing a local game 4v4 with a friend) I have stuttering every 10 seconds or so it locks up for about a seond. This does not happen in single player so I know it has to do with the handling of packets or something to do with the network. All my other games play just fine. Any ideas at what might fix this? I have realtek gigabit integrated ethernet by the way with the latest drivers.
I tried disabling my webshield and network shield in avast! and I tried running in compatability mode for vista sp2 to no avail.