Xbox and SMC Router Problems

I have a Xbox 360 and use an ethernet to wireless bridge (Slim Device.) All the network tests pass: MTU, NAT, DNS, ICMP, etc; however, the wireless network randomly disconnects ONLY during online games - nothing else. Other tests included downloading 2 GBs of files and that works ok. The ISP's upload never throttles down to cause disconnection. I have a SMC WBRT-14T wireless router and suspect it's either firmware on this and/or the Slim device. All other devices work wirelessly with no problems so there are no interferring wireless LANs, microwaves, mobile phones, etc. I have also tried every channel and auto channel selection. I purchased a Xbox 360 wireless adapter but that doesn't even pick up the SMC routers SSID on any channel but it detects other SSIDs. I use WPA/WPA2 encryption and will not drop down to WEP. Any ideas?