Since 2008 Web Wiz Forums has been developed on Windows 2008 64 bit, so the setup you have is the recommend setup for the mySQL version.
As you are having to change the driver from 'MySQL ODBC 3.51' Driver to 'MySQL' it means that the myODBC 5.1 driver has not been installed or not correctly installed on the server.
By changing it to the 'MySQL' driver it means that you are not using the myODBC 5.1 driver for mySQL and instead using an old generic driver which is not supported and will give errors.
You need to contact your web hosts and inform them that their is an issue with the installation of the myODBC 5.1 driver.
You also need to make sure that the app pool for your website is running in 32 bit mode as this is the recommend settings that Microsoft gives as it gives improved compatibility, performance, and memory management.