You may need to run database cleanup including reinitializing your databases for the particular site where this is occurring. Make sure that your recovery database is clear and any errors in the error database have been handled before doing this. You also need to shut down all processes. There may be less drastic measures you can take but in the rare instances I have seen this error I have had to schedule interface downtime, bring all processes in the site down, reinitialize the databases, and restart threads. I additionally clear vista.taf, monitorShmemFile, sem files, etc which are not critical but are good to do. I have steps to do this that I can send you if you want to reply with your e-mail address.
