This is more about your 64-bit ODBC driver than the PostgreSQL database itself.
This is more adapted on the pgsql-odbc list.
We are using version 9.03.03 of your 64-bit ODBC driver. We are finding that after SQLDriverConnect() with a bad password, the driver becomes unstable, and a second call to SQLDriverConnect() can (but does not always) crash with an access violation. I have not tried the 32-bit driver to see if that replicates the problem, which means I also haven't tried other products that support ODBC, because I don't know of any other 64-bit products with ODBC support.
This should be easy to reproduce. Have you seen that on Linux/Unix as well.