you should avoid WMV files and WMA files all together. because they are ethere advertizements. or protected and wont play unless you buy the song/video for a redicklus price,and even then the file is verry compressed and low qualety so its not worth buying. and some of them can even carry viruses.

however i do like the WMA lossless files so i will keep them if they arent protected.

to see if the file is protected or not just wait for it to go to 1% and hit preview, if media player comes up and dosent do anything or gives you an error message the file should be fine , if it comes up and ses "aquiring licence" or a browser window pops up just cancel the download because the file is protected .