I suspect that the piplay has set the pimax resolution too high for your graphics card capabilities. Can you please unplug your pimax hmd and then boot windows.
Then launch piplay and try to drop the resolution back down
I am surprised that hmd is not detected in safe mode as it is just another screen.. In safe mode you could try in piplay switch to video mode and then set the resolution lower
Basically in piplay mode it thinks you are playing games and needs all the drivers but safe mode allows basic drivers so it won't launch, but in video mode may allow you to get to resolution as it will load the monitors is basic resolutions.. Including pimax.
Hope this helps