HDP2.2 Appliance hung while coming up

Greetings!

I installed Oracle VirtualBox and HDP2.2 sandbox appliance. While bringing up the appliance, the rest of the system becomes barely responsive. The sandbox appliance gets hung at:
“Starting Knox Gateway”. I waited for about 30 minutes.

Any clue on why the appliance hangs there? What should I do to come out of this issue?

Thanks and Best,
Atul