I called tech support and they confirmed what Jim said. After a few hours of trying to get Windows Media Player working without success, I finally reinstalled Windows and now Windows Media Player works and I can preview styles with the preview player. A quick workaround tech support suggested was to change the double click action on the style preview page to load the style and play rather than preview it. That does help a lot, but getting Media Player working if it's not working is still the best solution for now.