If you want to watch a mms:// stream and windows media player gives you the following error :
Windows Media Player cannot play the file because the specified protocol is not supported. If you typed a URL in the Open URL dialog box, try using a different transport protocol (for example, "http:" or "rtsp:").
Here is the solution :
1.Click on Start
2.Click on Run…
3.Type the following command and press enter :
regsvr32 wmnetmgr.dll