As is happens, yes I do ;-)
Ask the question "What's an AVI?"
We'll, it's a container for either/both a audio and video stream. Each of these streams has a codec, such as xvid, divx, mpeg, h264, mp3, wav, etv. Certain media players only support certain codecs.
This can make AVI's a difficult filetype to work with (much like MKV which is also a container format). Other filetypes such as mov and mp4 are much more clearly defined from a codec point of view. Android (pre ice cream sandwich) supports Mp4 by default and little else.
But - there are tools that allow you to identify the codecs contained within a file, such as Gspot ( http://www.headbands.com/gspot/ ) so that you can find a suitable media player.
So what's the answer to your issue? You probably want to install a media player that provides support for a wide range of codecs.
Players I like:
Identify the codecs using Gspot to find out what's in them there AVIs and you'll be on the right path to resolving your problem.