unable to access a specific server ???

I have an ibook G4 with 10.4.11 and an AirPort Extreme
Wireless Card Firmware Version: 405.1 (3.90.34.0.p18)
Current Wireless Network: Airport Roger Wireless Channel: 12
I am also using an Airport Express V6.3
I am using 128 bit WEP and TCP/IP is configured using DHCP
IP address provided automatically.
I have the strangest problem. I have created two websites that I have hosted by a company in the USA. If I default my Express and set it up again, I can access both sites. If I leave the sites and try and access them again I get what's in the cookies but not any update. Clear the cookies and it will not load them at all. It is only these two sites and pinging the Host server also fails.
Remove the Airports from the equation and Connect using a cable and I have no problem. This is causing me grief as I cannot access the sites to update them nor can I access my webmail on them. I would appreciate any help on this problem