2010 Mac mini with Windows 10 . . . Black screen after reboot

I have a 2010 Mac mini with 320m nvidia graphics. I put a fresh install of High Sierra on there and its running great.

I then cut the (SSD) drive in half and installed Windows 10. I've done this several times now and it always goes the same way. The initial install works fine, I get to the desktop and I can use it, install software, whatever. But after the first Windows reboot, every subsequent reboot goes the same way... I get the windows logo for a few seconds, then no video. It's impossible to get it to work. I haven't be able to get it to boot into safe mode or anything.

I even tried installing windows 10, then installing the nvidia drivers directly afterwards before anything else, and then rebooting to see if that fixed the problem. But nope, same thing.

But if I boot into Mac, runs perfectly. So this has to be some kind of Windows problem. But I'm not a windows guy so I have no idea what it would be or how to fix it.