Simple WPA2 Wireless LAN. Two Windows 7, One Vista, and one XP PC. After a period of time, Windows systems cannot ping each other. They can ping the gateway and have Internet access. Windows networking stops working as peer system are unreachable.
Power cycling the WRTU54G-TM clears the problem for a few hours. Then it occurs again.
I would suggest you to upgrade the router's firmware and reconfigure the router from scratch.After upgrading the firmware,reset the router for 35 seconds,power cycle the router and reconfigure the router.