I have been working with Aperture 3 for a while. It occasionally freezes or crashes, but otherwise all is well. Today however the 'adjustment' panel suddenly went empty: all I can see now are the drop down buttons for 'Presets' and 'Adjustments'. I am not in 'Quick Preview'. I have repeatedly restarted my computer. I have restarted Aperture. I have deleted Aperture preference files in the library. I have repaired the Aperture library database. Still no luck. Any polite suggestions? Thanks.