Lock your workstation

 Batch file to lock the screen of your PC. Tested on Windows XP, Vista and 7. Works!

@echo off
%windir%\System32\rundll32.exe user32.dll,LockWorkStation
exit

Or

Right click an empty area of your desktop, choose New/Shortcut and enter this line as the command line:

rundll32.exe user32.dll, LockWorkStation 

Or

Windows + L