Write-Protection giving me problems

I recently downloaded some music off the internet and it works great on my computer, but when I go to sync it to the mp3, it gives me the following error: http://www.microsoft.com/windows/windowsmedia/player/webhelp/default.aspx?&mpver=11.0.5721.5260&id=C00D1236&contextid=211&originalid=80070013
I checked that none of the files are hidden, and they're all unblocked. I tried to drag and dorp it onto the drive, like I would to move it around on the computer or to a CD to burn, and it told me that the disc was write-protected. Can anyone tell me how I might take the write-protection off the disc to put the songs on my mp3? Thanks.
~Heather