belkin wireless g notebook problem HELP I YOU CAN PLEASE

I have a Dlink ADSL router( B Band) and I have connected a Linksys
(G&B BAND) to the Dlink ans it work fine so I have 2 wireless Networks
up and running, both using WEP encription. I am running a used Dell
L400 laptop with a Belkin wireless g card The lap top pick up the B
Band with out any problems
BUT..... when I switch the card over to the G band it log on to
linksys then the card all by it self changes is ad of a IP address and
will no longer connect to my wireless network instead having an IP
address of 192.xxx.0.5 to goes to 168.256.xxx.xxx

Any help here