Has anyone run into trouble using Zotero with Dropbox? I've been pretty careful to have only one instance of Firefox running at a time, but I seem to have lost a night's work. I actually don't even see a revision of the Zotero database in Dropbox to reflect that work - am I correct that when I close Firefox zotero creates the zotero.sqlite.bak file and then saves my work to zotero.sqlite? Has anyone else had trouble or advice?