Welcome to the forum.
As you have just found out, "AVI" is but a wrapper, and can contain all sorts of CODEC's - some standard, but some quite odd.
This FAQ Entry gives you background, and will help you determine what the exact CODEC is: http://forums.adobe.com/thread/440037?tstart=0
If you can use a file info program, like G-Spot, or MediaInfo, or Media Inspector (Mac), to determine exactly what the CODEC is, then post that info here, someone can tell you the best way to Import, or handle that footage.
Good luck, and please let us know more.
Please mention the version of Premiere Elements that you are using and on what computer operating system that it is running.
The readout programs will give you that information, but, if you have any problems with downloading and installing one of them, then please let us know the brand/model/settings of the camera from which this .avi is coming from.
I am guessing that your .avi is either AVCHD.avi or MotionJPEG.avi. But, the answers will be in the details that you supply.
We are looking forward to your follow up.
I had been thinking DivX/Xvid, or maybe one of the TechSmith Camtasia CODEC's, but your thoughts could cause the same issues too.
As you say, the information on the problematic AVI(s), will tell the tale.
Good luck to the OP,
I am having the same problem. It will work in Windows Live Movie Maker but in Premiere Elements 12 I only get the audio of the .avi file. Has anyone found a fix for this? It is very annoying.
We have yet to find out from paolo nussofatuzzo what type of .avi is involved in paolo's case. At least with your issue, we know that we are dealing with AVCHD.avi from an older camera. And, my recollection is that AVCHD. avi can be problematic.
As I mentioned in your own thread, we may be facing what you do not want to do, that is, convert the AVCHD.avi to another format using Windows Live Movie Maker. But, we will try to find alternatives.
More on this in your thread in the morning.