mid-2011 Macbook Air changes applications on wake from sleep
This is related to the System Preference for when it prompts you for a password when it wakes up.  Change it to never, and it goes away (less secure) or always (more secure, but a PITA).  Here's the link that helped me:

https://discussions.apple.com/thread/3268136?start=0&amp;tstart=0