Dropped network connection

We've recently installed a Buffalo TeraStation for file sharing via our

ethernt network in our small office. I've mapped the drive, turned off the

firewall, turned off the power management, issued permissions, gotten

everyone in the same workgroup, changed the computer names to avoid multiple

users and when the Appointment Calender refreshes the network connection is

lost, including any program that is using a (potenitally) shared database on

the TeraStation. Pinging finds the conneciton in a nanosecond. Closing and

reopening the program reconnects and solves the problem until the refresh

occurs. Using XP Professional SP2. What am I missing?????