categories blank after upgrade

During the database upgrade step (as I upgraded from wordpress 2.2.1 to 2.6), I received an error message about data in the wp-term table. When I brought my blog up, all the categories were blank. In the wp-term table, the stub field shows entries as ” “, “-2”, “-2-2”, “-2-2-2”, etc.

How do I recover my categories?

Thanks,
Ron