UR22 mkii and USB conflict

Hi, can anyone explain the strange thing happening to my UR22?
The fact: everybody konw that the plugs for USb in motherboards are at least in couple. Well, when I use Steinberg UR22 mkii with the second usb plug busy by another device (pendrives, midi controllers ecc), the UR22 becomes not stable, and often does not start 'till I launch a software that uses ASIO drivers.
It’s not a luck of energy, because I tried the audio card with a power switch and the behavior is the same.
This audio card is very good, but it needs to work alone, with nothing next to it.
Thanx for any help

I do not want to be ironic, but I wrote two posts since I bought Steinberg UR22 mkii. As you all can read are minor problems…but NO ONE answered me…in two weeks…
maybe “update your audio drivers, update firmware” or something similar. I’m a bit disappointed about Steinberg support and community.
Please let me hear your suggestions