Bah, that sounds like a pain.
I'd recommend hanging onto the money until the 45 day period passes. If there are no chargebacks issued until that period passes, I'm pretty sure you'll be in the clear.
When making sales with virtual items, it sometimes helps if you ask the person you're selling to if you'd be willing to chat in person on the phone before making the transaction. Frauds will almost never want to talk to a person in real-life, as it makes it a tad too personal for them (plus you have their phone number!).
For MAJOR transactions with virtual items ($50-$100+), I generally ask that my buyers send me a scan or picture of their driver's license or similar ID (I allow them to block all the information aside from the name and address). That way, I can personally verify that they are in fact the holder of the PayPal account. If they make a chargeback claim and you present that evidence, they'd need to demonstrate that whoever stole their PayPal account ALSO stole their driver's license... hardly likely. 😉
Best wishes of success to you in this matter!
