Need help with files...

Hello,
I recently got bit by a bug that made it necessary to reinstall Vista OS on a Gate way computer.
My problem is that when i am reinstalling music files off of DVD disk it isn't recognizing all of the files..
When i put a disk in that says has 1200 songs on it (mp3) and i get the prompt to view files it is only showing and allowing me to copy the 200..If i have a disk with fewer songs than a thousand ,no problem.
What can i do to recognize all the files or fix the problem.?
Thanks for the help..it is greatly appreciated as i am not that computer savy..