Great trick Lock ur PC yourself
lock ur pc.. open notepad copy and paste the script below and save it .VBS extention
This wil create a shortcut.. run(click) it
set WshShell = WScript.CreateObject("WScript.Shell")
set oShellLink = WshShell.CreateShortcut(wshShell.SpecialFolders("Desktop") & "\LockWorkstation.lnk")
oShellLink.TargetPath = "%windir%\system32\rundll32.exe"
oShellLink.Arguments = "user32.dll,LockWorkStation"
oShellLink.Save