I have 2 Windows XP Pro computers and 1 Windows 7 computer and these computers need to be able to transfer files across the network to each other. I have them set up and working. Mostly I have to transfer files from the XP computers to the Windows 7 computer. After a few days the XP computers cannot access the Windows 7 computer. I have to reboot the Windows 7 computer and after that all works fine again for another couple of days. Is there some reason after a few days the Windows 7 computer would for reason do this?