[iBook] network mystery

[Roger Harris]

I recently purchased my first laptop; iBook 500. It has an Air Port  
card, 256 ram, and I installed a 100mb 5400rpm HD.

I have been using it a lot in the last week. In my office In the  
office I usually Plug it to ethernet. I have DSL across the street  
and use a wireless access point to run internet and network for  
several Macs here and to the macs across the street.

As of last night the iBook has lost internet. It connects to other  
macs on the network just fine, but no web. Now the G4 tower it sits  
next to is getting a good internet connection and they are plugged  
into the same router and are networking each other just fine. But  
wait; There is more! If I unplug the ethernet form the iBook and go  
to wireless I can still network to all the macs. The wireless is  
connecting to the same wireless across the street that my Access  
point does. Why won't it get internet when everything else on the  
same network does?

I have tried all I can think of. I have trashed prefs, run utilities,  
pinged the router (100%), setup everything at least 4 times.

Roger