Xbox Live Problems, It gets "connection interupted all the time. And only works with Options

[Gerrigen]

Hi. I have a wireless belkin router which my xbox uses to obtain a wireless signal. I have altered the DMZ settings and enabled UPnP so I have open Nat. Unfortunately in CoD5 and 4 I am getting a connection interrupted sign 2-3 times a game. Each of these lasts for about 3-5 seconds. But on games without a dedicated server instead of connection interrupted I get booted from the match. As you can imagine this is very frustrating and completely ruins some games for me.

If it matters I believe the internet is run to my wireless router and then to my modem and into my main computer. two other computers and my xbox are connected wirelessly to my router.

It is also not a problem of IP's changing because I have the settings on my router to were it "leases" a IP to a certain Mac address indefinitely.

Also I tried port forwarding and my games still got connection interrupted.

I believe I have done all I can with the router so It might be my firewall. I use Kapernsky security instead of windows firewall.

I also disabled the routers setting to block ICMP ping.

Please help!