Oh, one more thing... To rule out the USB port on the computer as the cause for your problem, you should do the following, if you have not already.
Shut down (power off) your computer. Disconnect all USB devices (including hub), except for standard keyboard and mouse (if normally used). 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 computer.
Also, you can try connecting something else, preferably something similar like a USB flash drive, to the same USB port, to confirm it is working properly.