Mail and Messenger don't work over Wireless LAN

Hi,

I have recently installed a wireless LAN using the
Microsoft Wireless G Network kit MN-820. I have a gateway
PC connected to the internet via a USB satellite modem.
The gateway PC runs Windows XP home with ICS turned on.
The gateway PC is connected to the Base station via a LAN
cable. The base station is set in Access Point mode, i.e
routing, DHCP, etc are turned off.

At the other end of the wireless LAN is a laptop PC
running Windows XP Home using the PC Card wireless
adapter.

Using this setup, mail clients, both IMAP and POP, on the
laptop have trouble reading mail. Both clients login to
their server OK, but thenget hung up reading mail.
Generally no messages are received, but occasionally one
will get through. Microsoft Messeneger on the laptop also
does not work. Web browsing works fine.

On the gateway PC mail, messenger, and browsing all work
fine, so I think something on the wilress network
connection on the laptop is interfering.

Any suggestions ?