last couple of days, i have been downloading music files and when i launch the file, i hear about 10 secs in a voice over saying "music on demand" and sometimes it will show up again towards the end of a song.

Not every download just some, is this a new feature? How can i get a clean copy of a song?

i have tried several versions of a couple of the songs and the voice over keeps occuring.

And has anyone esle experienced this?

-Fltex

Sounds like spam. Do a search for the song titles (don't post the titles here) you've been downloading. The ones that you've downloaded will have a checked paper icon beside them.. are the files all the same size? You can use the junk filter to mark the spam as junk. Or try this hostiles list to see whether that cuts down on spam:
The TechNutopia Fullsize Hostiles List for BearShare and LimeWire

Try a new search for the files, search for artist or album rather than song title.
Stay away from files with heaps of sources - go for a file with 10 sources or less.
Check files with Bitzi before you download them, other users might've rated the files as spam.
How to use Bitzi

This thread has tips for finding music & movies.
How to find music

thank you i will try your suggestions