Sorry I forgot to mention this right off.
The G2 USB draws a lot of power. Try plugging it into different ports.
On my ASUS Hero XIII MB, the ports would work for awhile and then die, not to power the G2 again. In the end I ended up installing a PCIe add-in card that gets it's power direct from the power supply. I had the same problem on the Riff running on my Sandy Bridge so I already had the card.
My son on the other hand never had any problem with his G2.