User had Toad 8.0 which is able to connect an Oracle database without issues. User upgrades to Toad 8.6.1 but it is not able to connect to the database. Clicking on the "connect" button doesn't connect and doesn't give an error message. User is able to connect with SQL Plus and still connect with Toad 8.0.
There are no firewalls or anti-virus programs that may be blocking Toad.
Reinstall the Oracle client or upgrade it to the latest version.
