Payment made then refunded 2 seconds later?

[q59x]

At 23:40.06 last night I received payment and at 23:40.08 the payment was refunded. 

The buyer of my item is pretty angry saying he has already paid, but I do not have the payment as it was refunded for some reason 2 seconds later.

Can someone help me?

[q59x]

I just read the transaction statement and it says "PayPal reversed this payment because of a dispute or payment review. The money has been returned to the sender's PayPal account."

So I am still at a loss about what to do.