What is Windows Media DRM?
'Microsoft Windows Media digital rights management (DRM) is a flexible platform that makes it possible to protect and securely deliver content by subscription or individual request for playback on a computer, portable device, or network device.'
See:-Windows Media DRM FAQ
I can't find DRM Folder;what to do?
DRM Folder is present under:-drive:\Documents and Settings\All Users\DRM
But to view it you have to turn on the Show hidden files and folders option in Windows.
"Licenses for your media files are corrupted" or "License is either corrupted or not valid" error message when you try to play licensed media files