workgroup keeps losing network ID on Asus 500g and WL 138 link

I have set up an 802.11g link between 2 computers running windows
2000. I have an asus 500g router on one linked by wire to the ethernet
port of the computer and a pci asus wl 138 card on the other computer.
The radio link establishes without difficulty, but workgroup
communication between the 2 computers is very unstable and one or the
other fails to access the joint workgroup. The reason given is '
workgroup not accessible. the list of servers is unavailable. Or it
may say, unsuitable function. I have included IP addresses etc in the
setup.

Any suggestions or help will be gratefully received.

Thanks

Pete