Prasad at Work

This just happened to me yesterday after an update to the desktop client. I get this message on several notebooks that I had access to the previous day, one of which was a folder containing notes from staff meetings for the past several years. That notebook is somehow gone now; most of the others have the "You no longer have access to this notebook" message. I need access to all of these! Is there any known way of taking care of this yet? -Prasad