I have been having the same problem for a while at: http://www.zotero.org/groups/effective_education_projects/items but haven't had time to try and figure out what is going on. I hope that a developer might be able to look at this group and see what is going on.

I can still synch with my Firefox clients, although every so often, the database seems to go really funky, but after restarting Firefox, then the funkiness (items being in the wrong folder) seems to go away. I suspect there must be some type of corruption in the database, but I'm not sure where, or how it happened, or how to fix it.