Last week I have corrupted the database because on an unmounted volume. I have successfully repaired and got access to the database now but I am getting in all my actions in Bookends an window information telling "Nil open object" with an OK button. Therefore to get the job done I have to press the OK! I found that for database searches, web searches, etc etc. I tried to reindex, repair and rebuilt the databases. No change found.
I have looked in the forum and no one have ever reported such error.
It's hard to be sure from that description, but I'd try removing Bookends 10 Preferences from your Preferences folder and relaunching Bookends. If that doesn't fix it, please contact me directly for tech support.