I Don´t Get Nero

Why does Nero encode some avi files and not all?
And when i try to convert avi files to mpg files it takes a damn long time to do, is there a more effective way to convert?

So, can someone help me?

There are much better applications out there for converting avi files. Check out this site for options:

http://www.dvdrhelp.com/

Gives detailed descriptions of how to convert using several different programs, along with download links for those programs.

Try TMPGE for your conversion. It is quick and easy.