I started DL after a hard reset (DL wasn't running when I reset though) and it's showing the first time startup dialog.
I've checked the plist in Preferences and that the contents are still in Application Support/Delicious Library. Is there anywhere else which could be causing this? I have a backup of my whole home directory which I took a few seconds after I last added an item to DL so I have access to any files which went screwy.