Question:

What can you do as a system administrator to prevent the security issue that Bill must leave his desk many times a day to attend to business concerns; these absences are for varying lengths of time.; he has neglected to log off of his machine in the past, leaving it exposed while he is away?

A Set up a screen saver with a password that will activate when the system is idle for a certain period of time.

explanation

Utilize a screensaver with a password would be the best solution so that the computer will be protected if he does walk away from his desk.