Hub powers down and requires power to be unplugged and re-plugged to start working again.

I have started seeing a problem with my 7 port hub requiring me to disconnect and reconnect power before it starts working again. I have an older Mac Pro (USB 2.0 only) running OS X 10.10. It used to work fine, however recently, the hub will power down at some point after the computer goes to sleep. Since my keyboard and mouse go thru the hub (a 7-port USB 3 model), the only way I can get it working again is to unplug the power from the hub and plug it back in. This will cause the hub to power up and all is well.

I have seen a couple of posts about this but they are a year old and had no resolution.

Any ideas why this has started happening and what I can do?