There are a couple of things that come to mind with regards to this error.

Verify that the Salesforce user account you're using has the "API Enabled" permission. This is required to connect through the JDBC driver.

If your IP address is not included in Salesforce's trusted IP ranges, the connection will fail unless you append the security token to the password. Make sure your current IP address is allowed under Setup > Security Controls > Network Access in Salesforce.

You might also need to modify you jdbc url to include AuthScheme:

jdbc:cdata:salesforce:AuthScheme=Basic;User=myUser;Password=myPassword;Security Token=myToken;

In case the error still persists you can add logging properties to your connection string by modifying it to:

jdbc:cdata:salesforce:AuthScheme=Basic;User=myUser;Password=myPassword;Security Token=myToken;Logfile=D:\\path\\to\\logfile.log;LogVerbosity=3;

Once the Logs are generated please navigate to the error message to get more detailed information on this.