Transferring Music from my Lap Top to the Phone

Basic music transfer is easy. I've been doing it for awhile using Window Media Player, which I like.  Something has changed and now when I syc my phone with the Lap Top the music come out funny, sounds like garbble.  The old stuff previously transferred is still good and plays great.  Anything I sync now is garbbled.  I have tried without success to correct the problem. As I understand the Automatic Sync should mirror my library in Media Player, it does not.  I have a Dell Lap Top running Windows 7. The music on the Lap Top plays great, but when I transfer it, it sounds like garbble, even when I sync manually one album at a time.  Looking for some help.  I put in a big SD Card 16G plus the phone has 8G. I have about 15 full albums in the phone that play fine, would like to add some more.