Windows Xp Pro sp2 disconnects from network shares after idle time

I?m running a windows 2000 domain controller, and terminal services. I have joined several windows xp pro machines to the said domain. All is fine except, when the machines are left on over night, the network shares are listed but unavailable. I need to log off and back on again to restore the connections. I have removed all power saving setting, removed hibernation, removed the power setting from the nic in device manager, and ran net config server /autodisconnect:-1 what gives? Any help would be appreciated. Please note that I don?t have this issue with any of my 2000 machines. J.