*Sigh*
Turn the hold switch to on, and then off again.
Press Menu and the centre button for about 10-20 seconds until the iPod reboots.
As *soon* as it reboots press Play and the Centre button and hold them until the iPod enters the emergency disk mode.
Connect it to your PC, and then follow the uninstall instructions.
And take more care in future. The 80GB iPod says quite clearly on the back "80GB". *We* say quite clearly on the front page of
www.rockbox.org that this model is not supported.