Disconnect the hub, see if the problem occurs then.
If not, It could be the voltage fluctuation on the line that wakes up the Mini.
I have my mini running off of a P1900 Carnetix power supply. I have the button press simulation cable unplugged, so I am manually turning on and off the mini.
Turning off works as expected. I either hit the button or select sleep from the shutdown menu. No problem.
The computer wakes up by itself when I turn the car on. I have checked the power settings and made sure that "restart automatically after a power failure" is not checked.
Shortly after it wakes itself up, it just dies, as in turns off. Then I have to manually restart it.
I have an independently powered (off the 1900) USB hub.
When I plug the power button pusher cable thingy back in, I imagine it's just going to wake up by itself still and the power button press the 1900 does is going to put it right back to sleep.
It's your Hub or something attached to it that is causing it to wake up.
As for the "crash". Is it really crashing (check the console and system logs), or is the P1900 killing the power? Since you don't have the power button line connected, if the P1900 is still configured to sleep the Mini it could be getting out of sync and thinking it needs to kill the power when it should be supplying it instead.
That's kind of what I was thinking, Dave. The P1900 is out of synch with the start/stop cycle of the Mini and on wakeup it's killing the power after the time out.