Hello,
Yes the title seems to be something completely weird, but that’s really serious 
Is it feasible/possible to think about a Onyx PC feature which will shut down the PC after Onyx is well closed?
The need on behind is to avoid to be stucked at the next Onyx launch (if Windows is shutted down before Onyx quit everything properly, Onyx got DAX error (stuck at fixture group loading) and can’t run, that’s frustrating and arrive very often).
We’d rather fix the underlying bug. How exactly do you force this to get the Dax error?
Consoles have no shutdown command, just turn off power. Not sure how a PC would be different.
The exact scenario is quite hard, has it is not always reproducible.
But, here is a start:
Open Onyx, load a show, have fun.
Once fun is enough, close onyx, and shut down windows almost after you click validate to close Onyx.
Start the PC, and launch Onyx, load your previous show
As a result, you will get often stucked at "Loading fixture groups… " operation, with the Dax pop-under.
The same scenario can exists without the DAX pop-under.
I know that’s not a real help, but, i have not that much to provide 
hi,
For a work around on start up we created a batch file to run instead. This batch file runs HaltOnyx.vbs located in Program Files/Obsidian Control Systems/Onyx, waits 30 seconds then loads the Onyx software. This stops the error.
In Windows 10, a shutdown no longer is a shutdown as we knew it: to some extent it compares to a hibernate (which enables the fast start). So indeed, if Onyx didn’t have the chance to fully close by the time you shut down, there could be some process leftovers when you start your system again, prohibiting Onyx from starting properly.
This “hibernation”/fast start combination does not apply when you restart Windows (last time I heard), so if you encounter the problem, this could solve your problem.