Vista/XP/Mac/Linksys Network Crash

I'm running tech support for a network to no avail. Network consists of two Macs, both OSX, one desktop pc on WinXP SP2, and an HP laptop on Vista. Previously, the network was only the two macs and the XP system, all wired directly to a linksys router. Worked fine. Since adding the Vista system, the network crashes every night. When the network crashes, the router doesn't renew. The router is a linksys WRT54G. It is running 64-bit WEP encryption for it's wireless connection, and the two macs and XP system are still wired, with Vista over wireless. Does anyone know if the Teredo Tunneling Interface, or any other component of Vista could be causing the crash when it interacts with the Macs?