We have a Windows 2003 Domain with at least 250 domain members running XP. About 10% of these machines disconnect after about 8 hours (always around the same time of day) and then they cannot access the domain controller as it says the user is not logged in. They are spead all over the company on different switches so I dont believe its a network problem. They cant print, browse shares, etc until they logoff then back in. They do have network connectivity and can browse the internet fine. Since the clients are nearly identical I do not know what would cause some to have this problem and not others. Any ideas?