Connectivity to USB Dongle Lost - Intermittently

Hello - 

One of the USB drives in a HUB that contains multiple USB drives intermittently becomes unavailable. At times, it comes back online on its own, at other times a restart of the server console, or the service, or the virtual here client (right click->stop using->start using). Any idea why it detaches, when every other USB on this hub does not require this step?

Ping Settings

Server Ping Period 3 seconds

Server Ping Timeout 10 seconds

Thanks,

Chris