Unfortunately it seems that the new sticky note feature with the output preview in Acrobat XI uses the same keyboard shortcut as multiple selection tool in Pitstop (shift).
Closing the output preview is the easiest way to get around this issue.
We could consider changing the key for multiple selection in PitStop, but 'shift' is pretty much a default, so what could we change it too?
If anyone has any thoughts could they email me, I am the product manager responsible for Pitstop at Enfocus and my email is 'andrewb@enfocus.com'
All feedback gratefully received.