I think I`ve figured it. I`ve just checked the sysusers table of the DB in questiion. The suid of the user is listed as 19, however, in all the other DB`s the suid is 17. Which makes me think that, maybe this single DB was backed up or something, moved to a different server without that user, so you may be right about the orphaning problem. Is there any way of fixing it though without having to fiddle with the sysusers table??