2 pcs on network lose contact with each other: can still access internet

Hello,
I have a home network of 2 desktop PCs. One runs Windows 7 64bit, the other WinXP with SP3. Both have all current updates applied.
Both are wirelessly connected to a Cisco-Linksys WAG160N wireless router with Firmware Version:V1.00.16.

File and printer sharing are turned on on both machines. When the two machines are in contact, file and printer sharing works fine and they appear on the Win7 network map.

However, they regularly lose contact with each other BUT they both remain able to access the Internet via the WAG160N and appear in its ARP/RARP table.
I get no error messages, but I can see that contact has been lost when I expand the network in Windows file manager.

I can overcome the problem by powering the router off for 10 secs and then on again.

I have had this problem for some time – it also occurred with the WinXP desktop and my previous (laptop, XP) machine.

Does anyone know how to fix this?



Cheers