Hello guys.

This time I request some help because I'm trying to convert some avi files into mp4, but once i do it with mencoder, ubuntu cannot play the mp4 file (although i can play other mp4). It doesn't play ONLY the mp4 files a made with mencoder.
On the other hand, when I try to use ffmpeg, it says "Unsupported codec for output stream #0.1", not allowing me to convert them.

What should I do right now?

In previous releases of Ubuntu I did this kind of conversions so easily with no problems, what's wrong this time?

I'm using Ubuntu 10.04

Please, give me a solution as easy as you can, like apt-get install whatever, etc