When clicking at SQL Navigator Logon Screen, I cannot see the database drop-down list; however, I can still get connected to database if the connection information is typed in manually.
Go to Start | Run, type in Regedit, and look under HKEY_LOCAL_MACHINE, SOFTWARE, ORACLE, ALL_HOMES: If more than 1, multiple Oracle homes exist, such as ID0, ID1, ID2, etc
NOTE: If you have multiple homes, then make sure to add the TNS_ADMIN to the correct home being used. For example, HOME0.
1. Choose HOME0
2. Right click on the right pane of HOME0 for New | String Value
3. Type in TNS_ADMIN
4. Double click TNS_ADMIN
5. Type in the path to point to your tnsnames.ora file. It should be something like this.
NOTE: Starting in version 5.0, there is no need to modify the Registry as the connection screen now allows you to select the desired Oracle home, this is especially useful when working with Oracle 10g clients.