Kathy when you set up this new computer did you complete all the actions required for Windows 7 and Hoster?
Here is the link:
http://www.mtu.com/upgrades/hoster/windows7-changes.htm
It maybe because these playlists were copied to the new computer that Windows 7 is not giving Hoster permission to open them, so they come up as blank. The link above has steps that should correct this.