How to manage audio drivers priority ? (USB & Motherboard)

Hi, i have a problem while using the ASIO drivers for the Zoom H Serie (H4n) (It don't seem to be matter with ASIO drivers especially) but with the fact of there is two kind of audio flow : USB and motherboard in/out. I think there is a conflict beetween both, because of Windows (XP) and that mean it have to be managed manually... Note : the ASIO H Serie work very well, but only when freshly installed. If the Zoom plug off : Realtek'drivers back on priority, and if i plug the Zoom on again : nothing happens. (I have to restart, and reinstall ASIO driver to make it working) Well, seem to be a newbie mistake like "check the right audio device in Reaper' settings" but no... Note : I also have ASIO4All, and it work perfectly, on any time, if selected (because it's no USB) It's not the case with ASIO H Serie : The Zoom device is not detected. I guess it's simply a conflict beetween USB and Realtek drivers, I tryed to fix it with basics windows options, but no way. (through about editing the registry on ksolay.ax, but i'm not enought experienced) Do someone have an idea how to fix it ?

Do you still need the onboard Realtek sound device ? If not, I would turn it off in BIOS and uninstall the driver. (That's what I did, because I never use it) If you need both you could try temporarily disable the Realtek in Windows device manager while you use the USB device.

Edit : Okay it works I just disable Realtek from the Windows device manager, and unchecked "use default device only" in audio' control panel. Now i have choice, by simply clicking... Thank you :)