Basic situation is a QB file hosted on a server, QB is not installed on the server. Never more than five users on at any one time. When office is closed at end of day all machines are logged off Quickbooks. Owner will sometimes remote in and do work at night, after hours. More than likely, he will leave his machine logged into server overnight. Upon, opening office in the morning, first person attempting to log in will get an error, and cannot log in until I do a server reboot. Occasionally, it will allow them to log in, but will lock them in single user mode. This is Quickbooks Enterprise 20, updated to latest patches. Any ideas as to what would cause this issue, or a way to troubleshoot the issue.