No one has answered you, so I'm going to take a "stab" at it. I know that you can search for individuals linked to Citations. The Citation Search window lists all sources in the Source library, perhaps you can actually search for citation no. 100 and take a look at it. There may be a strange character or something there (sometimes if it's blank, even a space will fowl things up) that makes the program give you the message when you use the check utility. I believe you can also check for Individuals, events or ALL (I would use the all option myself). Hope this helps you.