The following error occurs when opening Schema Browse default at Tables tab:
"ORA-01722: invalid number"
Tables list does not show. If Schema Browser is set to Treeview on the left hand side, error does not occur.
1. Select View | Toad Options menu option
2. Drill down to Startup section
3. Change “Check for access to DBA views” option and hit OK
4. Close and reopen Toad