Brand-new Nano won't stay open in iTunes

[ianfreeman]

When I connect my Nano to the computer, all appears well. iTunes starts up and the sync process begins, but as soon as it finishes iTunes displays "Sync is complete, OK to disconnect" and the device then disconnects itself.

This means I can't delete individual songs or do anything that doesn't involve a sync.

I have tried every process described here http://www.everyipod.com/ipod-help/index.html except that I cannot get the Nano to go into disk mode - holding down the appropriate buttons has no effect.

It's only two days old, but before I return it to the shop might anyone have any ideas?

TIA,

Ian