MP3's can be protected or not protected, protected does give all kinds of problems.
In Windows file manager, or whatever they are calling it now, if you open your directory and list all of your MP3's, can right click the name bar with a bunch of selections listed. Click Protected on, this will tell you if your songs are protected or not.
I do not have this protected problem, been buying my own CD's since around 1987, and using either Windows Media or Nero to rip off the tracks as they call this, they are not protected. Also use the MP3 suffix as opposed to wma, wma gives problems. Rip at 192 KB/sec for high quality. Also have that San Disk Cruzer, several of them, nice and short, and can sure put a lot of CD's on it. Sure beats driving into a tree trying to find the CD scattered all over your vehicle trying to find a song you want to hear. Cruze follows the directory format. Have like Classical, then a bunch of classical albums listed, then the songs so use Folder view. Ha, also Rock and Roll folder, but not Rap yet.
Another problem, know this because I have a ton of kids, is downloading MP3's loaded with a virus, dad, why did my computer crash, can also crash an MP3 player. *.jpg files can also be loaded with a virus crashing your computer, okay to view them on facebook or My Space, but if you download them, you may have major problems. They also store all their crap in Drive C, stupid, when that crashes, they lose everything. Won't listen to their dad.
Some can be recovered by pulling the HD with another computer, but don't use a good one, may crash that one as well.
Welcome to the digital age.