Reset external monitor settings (Lion)
Locate
    ~/Library/Preferences/ByHost/com.apple.windowserver(UUID).plist (may be 2x) 

as well as 

~/Library/Preferences/ByHost/com.apple.windowserver(UUID).plist.lock  

Put both in trash.

Empty trash.

Restart.

This most likely will not change your graphics settings; however, it was my experience that doing this whole process in "scaled" display from the beginning, allowed me to go back in to settings after restart, and choose "Best for display" and resolve my issue.
YMMV
10.9.1 - mac Mini with 2x displays; orig. issue: best for display output 'out of range' on 2nd display; native settings verified.