If you got exactly the same result–e.g. an error message in glGraphicsStateGuardian.cxx–then you must have modified the wrong Config.prc, since if you had set to use DirectX mode, it wouldn’t have been running any code in glGraphicsStateGuardian.cxx. Look around for a different Config.prc file. There might be an application-specific Config.prc; look for that one also.
David