How to lock Windows 7 session with just key strokes?
Solution 1:
Windows key+L should do what you need.
Solution 2:
Use Windows+L. If you use AutoHotKey you can reprogram Windows+L to do other things too, like lock your session, and also wait 10 seconds and put monitors to sleep. Powerful little hotkey program.
Solution 3:
Also, Ctrl+Alt+Del, Enter and Ctrl+Alt+Del, Alt+K seem to work for me.