Toad for Oracle or Toad Data Point on Windows 7 64-bit. Gets error: ORA-12557: TNS protocol adapter not loadable.
WORKAROUND 1:
Right-click My Computer | Properties | Advanced System Settings | Advanced tab | Environment Variables | under 'System Variables' | look for an "ORACLE_HOME" entry | rename it to "ORACLE_HOME_OLD" | click OK until you have exited the window.
WORKAROUND 2:
If there are more Oracle Clients, check if the PATH variable points to the same client as a client in ORACLE_HOME variable. If not then fix it to use the same client.
Value for PATH is <ORACLE_HOME>\bin.
BOTH SOLUTIONS:
Next, restart Toad and then re-test the issue.
