In most instances, this issue is isolated to Laptops.  Many laptops run USB power below USB spec in order to save on battery life. It isn’t a issue  as most things do not use USBs full capacity of power, or even close to it.  If you are on a laptop, retest on a  POWERED USB hub (has a AC power adapter, not getting it from the USB) and test running the UV+ off of that if you ahve one available.  In most cases this is the fix.  You can also test this on a regular desktop PC.  If it works there and not on a laptop, a Powered USB hub is recommended.