I have an issue with my Matrox G200 where if I use PowerDesk 4.10.007 or 5.55.022 and DirectX8 it will not shutdown properly, and hence, DirectX 8 never truly gets installed properly, but directX7 ...
you can't. DirectX is part of the operating system, so you'd have to reinstall. I remember seeing a utility somewhere that purported to uninstall DirectX 9, so you might google for it. Use at your own ...