I have an external Dell monitor connected to my MacBook Pro that runs OSX 10.8.4. My MacBook screen is set as the primary display, the Dell as the secondary. Sometimes after sleep the secondary display "resets". The wallpaper changes to the default milky way one and all the apps that were open there are moved to the primary display. I have to replug the Dell in my laptop such that it gets recognised again.
I'm mostly annoyed by the apps moving to the primary display, as I have to arrange the windows again on the screen. How can I prevent my MacBook "resetting" the secondary screen (except for not letting the MacBook sleep)?