This is a very small build that I particularly like.
It's a VIA EPIA-TC with a Nehemiah CPU, to which I added a Radeon 9250 PCI video card with a 90° riser card. All fits in a very small casing.

I'm using the DVI output and I'm a facing a strange problem.

Whenever I'm on Windows XP, if I switch my monitor to a different input (to use a different computer while this one is still on), Windows XP makes the "device plugged in" sound (the same one you hear when you plug in an USB device). That's strange. Then, when I switch my monitor back to the Radeon 9250 output, I can hear the same sound again, but the screen stays blank and there's no signal.

If I'm on DOS this doesn't happen. I can switch between different inputs freely on my monitor.

I think this is due to some Windows setting or driver configuration that I couldn't find. What could it be?

This problem doesn't happen on XP if I'm using the Radeon's VGA output, but that's not convenient for my current setup, so I wanted to get the DVI output working normally.

On a side note, the on-board IGP can't be disabled from BIOS unfortunately. I tried to tweak the BIOS but I couldn't find a way to do it. I've already disabled the device on Windows but still I wish I could disable it from BIOS to get more performance out of this little board. This is the BIOS for reference in case someone could give a hand. https://theretroweb.com/motherboards/s/via-epia-tc#bios