I had the same problem. I am not sure how my tables got corrupt but I lost "params" and "activation" columns in addition to having to reset the auto-increment in the extra field.
I suspect my issue was caused with using both the joomla and CB login forms. I had to track down other notes to identify the conflict of the two mods running simultaniously.
Thanks for your posts... the bread crums lead me to fix my issues...
CN