machine keeps losing network connectivity

[PhilthyPhil]

One of my machines keeps disapearing from my network and since I only connect to it by remote desktop I keep having to reboot it. It says the following in event viewer:

The browser was unable to retrieve a list of servers from the browser master \\PHIL1 on the network \Device\NetBT_Tcpip_{3B273474-CA72-4D25-826D-774CCF4B5706}. The data is the error code.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

PHIL1 is my main box, but I don't think it is anything to do with that as I had the same problem and message when I plugged this machine into a mates network except it had his hostname instead. This is with XP pro

anyone know what could be causing this, i am very