The WMA's you downloaded from MSM Music are actually WMA DRM's (Digital Rights Management) a.k.a. "protected" WMA's. I have a Creative MuVo N200 and I buy music from walmart.com, buy.com, and msn music and have not encountered any problems. If you go to http://www.playsforsure.com you can see a list of mp3 players that have been certified to play WMA DRM's. Unfortunately, your iRiver flash player is not listed. I checked the iRiver web site and it said that your player could play protected WMA's. You may want to update your firmware, or you may have loaded your wma's into your player without the iRiver software, I don't think you can load the songs on the player by clicking and dragging. If those things don't work call iRiver tech support.
I recently bought an Iriver ifp-899 series player. I downloaded WMA files from MSN Music and they copy. However, they won't actually play. I went to their website and it said it might be because they are protected files. Does anyone know how I can transfer them to my player? Thank you.