Last problem, I swear

[XspitfireDemonX]

I know i've been coming here with alot of problems, and I apprecieate all help and patience everone has had with me. This will be the last problem i'll bother people with, promise. The audio problem is that I fineshed my newest vid and everthing is great when I export. But after I compress the vid in with Xvid the audio plays only half way through. When it gets to a third track the audio goes dead. But if I skip right to the third track without the first or second track playing it runs fine. When I compressed the audio with MP3Lame I couldn't find the exact kbps so I got the closest thing to it, could this be it?

Thnx for all help ^_^

-Ryan