also your iPod touch may not have the latest firmware. If after updating your iTunes software it is still not recognized then go to Apple’s website and in the support section do a search under iPod touch firmware. You should also find the instructions there for how to flash (install) the firmware from inside iTunes and from outside of iTunes as well.
Make sure you’re not running any third-party applications that may modify how devices are mounted on your Mac (MissingSync comes to mind). iPod hacking utilities might conceivably be causing a problem, too.
well alot of the procedures above may work what I would do is restore your iPod by holding the home and the sleep button until the apple sign appears and if that doesn’t work I would call apple and ask them and if they can’t help return it for a new one…good luck.