Hey
to me this sounds like a fault in the hardware, i had this same problem with my first
zune 80, it crashed a lot and wouldn't connect to the software even though it was shown in my computer and charging properly. Your best bet is i guess first to check that your usb ports are all 2.0 or above, then try it on another computer and finally give in and hope the place that you bought it form will give you a replacement or a refund
that was the hardest part for me, convincing amazon to ship over seas, paying for all the deliveries and nearly getting sued because the check we sent got lost in the post ??
hope you have better luck