When calling the TB address book the personal address book displays but the block that is generally to the left and displays a choice of books (Personal, Contacts, etc.) is absent. However, when Write is called the choice screen displays and the various books are present. I have tried removing and reinstalling TB, purging TB and reinstalling, and disabling add-ons, etc. None of these maneuvers helps. However, going to safe mode 'fixes' the problem but then disabling everything and restarting does not restore the screen. Suggestions appreciated! Ubuntu and Thunderbird current versions.