Other system Preference windows work fine, but every time I open the Desktop Prefs to change my wallpaper selection, it crashes System Preferences. I've run checks on both my startup HD and the external HD where my wallpapers are stored, and both are fine. I've shut down and restarted, repaired permissions, and still the weirdness. i've used this same setup (Mini + WD external drive) for 2 years now and this has never happened before. Any help deeply appreciated. Thanks! UPDATE: Okay, I figured it out. I deleted the Desktop Caches Library and it's working now.