Major Sound Problem when previewing

I downloaded many music video’s from Limewire and various torrent sites and burned them all to DVD disc using Roxio EMC 7.
Now I want to re-do this video collection in order to create a preferred running order. However, when I try to upload these video’s and create a project what I get, upon previewing the video’s, is a nasty sound problem. ‘Clipping’ I believe is the correct terminology. A ‘crackling’ sound. As a wee experiment I burned 1 of these video’s (that had already been burned some time ago using Roxio) and played it on my DVD player only to find that there was no sound at all only video. Why ? :confused:

Silly me, but I completely forgot to mention that I want to re-do this collection using my newly purchased Nero 7 Premium Reloaded - I dumped the Roxio programme. The problems described above are with Nero.