Yesterday, I just installed the latest version of Qubes (when I booted up, I chose to install with the latest kernel).
Once I log in, for some reason, I wasn’t immediately able to scan and connect to a network so I tried to start sys-net but got an error message. See the attached image below.
What’s your hardware? (not related to the USB question) Maybe it’s missing features to run virtual machines in Xen, and that’s why you couldn’t start anything.