DELL XPS 13 (9380) no picture and computer stops working after plugging in HDMI

My XPS 13 (9380) is less than a month old. I have these problems since purchasing the USB hub and connecting a HDMI cable in. Two things happen:

- The picture gets displayed on both monitors (everything is OK)

- Picture doesn't get display on neighter monitors (I have to hard reset my computer in order to work). It seems like the computer stays on (keyboard is on), but I cannot do anything since there is no picture.