Music files being synced do not match

Hi There,
I'm having trouble trying to sync my music folders from my computer (Windows
Media Player) to my phone (HTC Touch Pro). I have been able to sync them in
the past, but as I updated my music file on the computer and removed some
songs, I noticed after I have done the sync, I check my phone and the deleted
songs are still on my phone and some of the new songs are not even showing
up. The process shows each change being synchronized on the computer when
the device is connected, but once its finished, the changes don't seem to be
made. Could you please tell me what else I could do? I did try manually
deleting some songs from the phone itself, but when I came back to it later,
the deleted songs reappeared! I want it to look like my file on the
computer...please help!