This is a trick to lock an XP based workstation or server without using a screen saver. The problem with the screen saver comes when using scripts like AutoIt3 which interact with the screen. Screen savers effectively block scripts from interacting with windows, but just locking the workstation does not. When mixed with turning the monitor off this is an effective method of protecting the workstation or server.
Create a new scheduled task (Start/Programs/All Accessories/System Tools/Scheduled Tasks).
Add the task:
C:\WINDOWS\System32\rundll32.exe user32.dll,LockWorkStation
Use the starting directory:
C:\WINDOWS\System32\
Run as an Administrator account
Click the schedule tab
Select “Daily” and “Every day”
Click on the advanced button
Repeat the task every 20 minutes (or however long you want the computer idle before the workstation locks, roughly)
Set the “Duration” to be 24 hours
Select “OK” until you return to the Scheduled Task window
Select the settings tab
Under “Idle Time” check to “Only start if the computer has been idle for at least”, and perhaps give it 15 minutes and maybe 40 minutes for “If the computer has not been idle that long, retry for up to:”
That should do it.