another thing to check is content protection. Windows Movie Maker (WMM) doesn't allow use of files that are content protected when riped by Windows Media Player (WMP). Go into WMP and check the content protect settings. then check the individual file(s)'s settings. If it is ripped content protected, you can't change it. Delete the file and re-rip it without content protection. Otherwise, WMM recognizes WMA and simillar files automatically.