In PM 4.6.1 beta 5 (and previous ones as well) on my Windows XP netbook I am unable to move (Space pressed drag of the image not the crop) the zoomed in preview in crop mode. If I deactivate the crop mode, panning works. I checked on OSX as well it works properly.
I have no other Windows machine to check it now, but I doubt it would be caused by the netbook fact.