Problem after switching router

Hello everyone,

I recenty replaced a router for my friend. He was using a Belkin Wireless G+ MIMO Router. I bought him a Linksys WRT54GL and when I hooked it up I did my best to carry over all the settings.

The whole hooking up and setting up went fine. But when I try to connect to the internet it wont work. The strange thing is that I can see the network and I can connect to other computers that are on it. But no luck with the internet.

However I can switch it back to the old router and it works fine. I also can connect to a neighbors router and get to the internet.

Another weird thing is that a Internet Gateway subcatagory appears with a Internet Connection icon in the Network Connections window. When Im connected to the other 2 routers (the old one or the neighbors) the Internet Connection automatically enables and works fine. When I connect the 54GL though, the network connection goes ok, it gets the IP and DNS and all that stuff but the Internet Connection just stays disabled. I can right click and choose enable, then a dialog box comes up that just says "connecting..." then after a few seconds it says "connected!" then the little box disappears. However under Internet Connection icon it just stays at "Connecting..." then after like 30-45sec it goes back to disabled.

Heres some of the stuff Ive tried.
- Pretty much all combinations of power cycling, restarts, and doing the network repair
- DHCP is enabled and its not conflicting with anything anymore (I had to change the starting range because when I first plugged the router in the computer came up with a IP address conflict.
-I copied the MAC address.
-Resetting to factory defaults
-I did my best to transfer all the setting from the origional router, as far as basic setup goes(MAC address, IP, and DHCP)

The only thing that I can think of about my friends setup is that he has the Comcast Voice modem so the modem is also hosting his phone service. I know this is were the problem is but I cant figure out what to do.

Any advice would be appreciated. Thankyou