This has just happened to me for the second time. it seems to tend to happen when the N900 gets frozen and has to be power cycled (typically during processing by Panorama or BlessN900), presumably due to corruption of the database, and once it has started, it's hard to get rid of. in fact, i think i ended up flashing last time and restoring an old backup. I'd prefer not to have to do that again because i don't have a recent backup preserving some important SMSes. What have people found to work?