How did you upgrade? did you run the update scripts as the MySQL doducmentation describes it after the upgrade?
When you click the + of a database SQLyog sends
Code:
select `TABLE_NAME` from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_SCHEMA` = 'your_db' and `TABLE_TYPE` = 'BASE TABLE'
(bacause that is the way to distinguish betwenn tables and views)
what hapens if you execute it as plain SQL? Looks like a defect information schema or a privilege issue.