Users have a lot to worry about when downloading and playing media files. Are the files legal? Can their computers play the required file formats? Now there's yet another problem to add to the list: Will a media file try to install spyware? When Windows Media Player encounters a file with certain "rights management" features enabled, it opens the web page specified by the file's creator. This page is intended to help a content providers promote its products -- perhaps other music by the same artist or label. But the specified web page can show deceptive messages, including pop-ups that...