This applies to Vista users.
I don’t know why Microsoft has made it this way but you just double click empty space in your tray and bang! Windows Defender opens telling your computer is safe. Of course, I’ve never asked it to scan. Or it does it automatically. Hmm.
Click somewhere here. ( The red portion and on your tray, not on the pic. 
) Mostly works below normal tray icons and not below Volume/Internet/Date icons.
