Disconnects me from online games?

Hello norton community. I recently built my own pc using some decently new hardware so I could play the latest games. ( COD4, Battlefield, Warcraft) But am having a really frustrating issue. Every time I join a multiplayer game on any game, I will be able to play only from about 5 minutes to 10 minutes before It disconnects me.

--I used to have a laptop that was ancient, and this would never happen so it couldnt be my internet connention. I use a cable modem at 100mbs directly connected to my pc.

--I used Norton internet secruity for my new build and am pleased with it but have come to beleive it must have something to do with my disconnection problem.

-- I tried allowing certain game ports through the firewall but It hasnt resolved the issue. I also have a program that watches the temperatures of my hardware, after monitoring them, its not a heat issue as my GPU runs solid at 45c to 55c. ( HD 5770 ).

--All of the games I play run flawless in single player, but multiplayer is really what I built this PC for.

--I use windows 7 home premium 64-bit ( system builders ) My other specs are: Intel core quad i5-750, 4gb ram, Asus P7P55D, 650w power supply, and a single Radeon HD 5770 DX11.

--Everything is running great and have had no problems aside this connection issue when online gaming. Anyone else had this problem or a similar one? Could it possibly be the firewall or another feature of NIS 2010? Any help or advice would be appreciated as I am on the last straw with this issue. Thanks, -Dan