The buyer has registered a Paypal dispute against me.  I have responded with a copy of the Australia Post receipt and tracking number, and have requested Australia Post provide a copy of the signed delivery receipt (which I'm assuming is possible).  Is there anything else I can do to support my position?  And can I just say thank goodness for the forums.  I emailed ebay, and after several days I received a response saying I had nothing worry about.  Is it worth trying to speak with someone at Paypal?  It really isn't easy to get information from either ebay or paypal in this situation, but thanks to the forum folk, I'm feeling a little less sick about this disaster.