Wireless "Adhoc" mode

Have two Netcomm NP5420 54Mbps Wireless PCI cards in two computers. Trying to establish an "adhoc" connection between the two PC's. Both have the same workgroup name, both have individual names, both have IP addresses....ComputerA can ping ComputerB, but ComputerA can't ping itself, ComputerB can't ping ComputerA, but can ping itself! I have disabled the built in Windows XP Wireless Zero Configuration on advice from the Netcomm site, have disabled both onboard ethernet controllers, both are running Windows XP SP1. They both have File and Print Sharing enabled.

Is there any firewall software on computer A which might be causing an issue?

What is the "ipconfig /all" output on each machine?

Disabled the built in Windows XP firewall on both PC's. IPCONFIG shows correct IP address for each PC....very strange.

Are you running any third party firewalls such as Norton Internet Security, Sygate, or ZoneAlarm?

actually the client is running Norton Internet Security. I will disabled that later when I'm there.