From your mobo manual, page 37, it clearly states it's a memory issue. I take it as a drain on the CPU power which is throwing up the error message as the system doesn't know how to report it any other way. Because you're using the USB hub.
As for issue with using the USB hub. As you state, all other USB ports are empty, why not just use the USB ports on the I/O area (back of tower), you've got 6 USB ports back there. My guess is; that this USB hub does not have it's on power source and filling up the hub with all those devices uses a lot of power. My question is why do you need a USB hub if all your mobo ports are open/not being used?

As for issue with using the USB hub. As you state, all other USB ports are empty, why not just use the USB ports on the I/O area (back of tower), you've got 6 USB ports back there. My guess is; that this USB hub does not have it's on power source and filling up the hub with all those devices uses a lot of power. My question is why do you need a USB hub if all your mobo ports are open/not being used?