Can I use an automated procedure to disconnect all users from my server at a certain time each day?

Yes. Run the Net Session command to receive a list of all remote users and computer names connected to your computer. To log those users off of your server, type

net session /delete /y

The /y parameter instructs Windows 2000 not to ask for confirmation before disconnecting these users, which means that you can use Task Scheduler to configure the command to run without your intervention or oversight. Note that this command logs off all remote users, even those who have files open.