Microsoft's Zune HD is already encountering sellouts less than a week into its availability, according to multiple reader reports. At Amazon, the 16GB modelremains in stock but the 32GB version is already facing a one- to three-week shipping delay. Visitors to Fry's see a reverse situation where the 16GB model is out of stock; the worst affected so far is Best Buy, which claims to be "backordered" for either capacity.