Craig
Anyone that receives credit card payment is on the hook for fraud, the only other way that could happen would be the issuing bank would be responsible and we all know that's not going to happen.
Regardless of the circumstances of your transaction, had the person who sent you the payment shown an "eligible" address on their PayPal payment, and had your shipped to that address within 5 or 7 days (I forget which) and if you had shipped using a method that gave you online verifiable signature confirmation, PayPal would have held you harmless in that fraud dispute. PayPal's "investigation" of all credit card disputes stops at verifying if the seller has jumped through the aforementioned hoops, if the seller hasn't, the seller is on the hook and PayPal will wash their hands of the matter and the seller is out the money. Maybe its them "doing nothing" to help you, but in fact is is more than your bank will do for you if you have a credit card terminal and a merchant agreement through them.
Kevin