Change logoff time for computers/servers on the domain

If you are running in a domain environment, create this setting accordingly in a GPO, otherwise configure the local GPO (gpedit.msc):

Computer Configuration -> Policies -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> Interactive logon: Machine inactivity limit

If you want to prevent lockout set it to zero, keep in mind the security impact this change can have dependent on your environment.