So if I understand this, he put an item up for auction and you won, then he claimed you didn't? Or that he never had the item to begin with? Was this multiple auctions, or multiple items in a single auction?

It could be an honest mistake, but my cynical mind thinks it sounds like his version of a reserve price auction. Not enough bid, so you didn't win.

At the very least you need to notify someone at Ebay and have this investigated for possible account revocation. Unfortunately not much else you can do.

If it was chip related, you may want to post his ebay handle (and real name) so that we can watch out for him in the future.