You need to find out what kind of .avi file that you have. Not all .avi files are the same.
What is the model and settings for the Nikon that recorded this video.
If your have AVCHD.avi or H.264.avi, that is not supported by Premiere Elements.
MotionJPEG.avi can be problematic for Premiere Elements at times.
Please supply the above information, and we will help you determine the cause of the problem.
AVI is a wrapper, what is inside YOUR wrapper - Exactly what is INSIDE the video you are editing?
Codec & Format information, with 2 links inside for you to read http://forums.adobe.com/thread/1270588
Report back with the codec details of your file, use the programs below... A screen shot works well to SHOW people what you are doing
https://forums.adobe.com/thread/1070933 for screen shot instructions
Free programs to get file information for PC/Mac http://mediaarea.net/en/MediaInfo/Download
You should not have to go through the bother of downloading video audio properties readout programs if you know the Nikon/model/settings of the camera that recorded your video. The Specification for your camera that we can access quickly should easily give you the information that we need to help you.
But, if you cannot obtain that information, then that is another matter.
Looking forward to further details.
Thanks for the response,
I was provided the video by someone who simply said they had a Nikon.
I went out and reshot the video with my own camera. Thank you though,