Did this work before on this computer and does not now for some reason? Or is this the first time you are trying to use this iPod with this computer?
The latest iTunes is installed, correct? If not, you can download it here
http://www.apple.com/itunes/
As a test to confirm there is not a problem with the USB port, such as lack of power to operates the iPod and charge its battery or USB device conflict, try the following. Shut down (power off) the computer and disconnect all USB devices, including hub, except for standard keyboard and mouse (if normally used). If your computer is a laptop, connect its power adapter (so that it's not running on battery power). Do this to reset the shuffle
http://support.apple.com/kb/ht1655
Start up computer, run iTunes, and connect shuffle to a direct USB port on the computer.