We are not sure what is causing the MST Hub to make your system to stop responding. There is a trick that I always do when this happens but I am not sure if it is going to work for you.
Please power down your system, unplug your power cable from your system and press the power button to drain off completely your computer power. Then reconnect everything to see if this resolves the problem.
Check if on another PC the MST Hub is working properly.
If defective please have it replaced inmediately.