I can confirm i have the same problem. For me it seems as if i put more than one thing to download/stream and the connection gets to max load something goes haywire. The Network loses connection. If I'm just running one program at max DL at a time it runs fine.
Hmm, Will have to see if i can find some drivers, read a guy who said manually installing drivers might be better than those driver packages.
I run a Asus P5N-T Deluxe Motherboard - 780i Nforce, and am running the ethernet on it. The router is a zyxel (something) but am almost certain that it is not the router which is the problem.
I'll report if i find anything.