Can't import avi video file! Need help!

I got a video on my old computer using Pinnacle software. I have then saved my video file to a portable hard drive and am trying to import them into Movie Maker. I am getting some error mesasge "Windows Movie Maker has encountered a problem and need to close." Can anyone please help me out? Thanks.

Is there Windows Movie Maker work with your other projects or files? If not then you might have some problem that needs to be addressed first? In any case, you have a codec problem and the following free utility will identify the codec that you need. You can use something like GSpot.

Thanks, I am able to import photos and music and I am pretty new at this, so can you tell me what is a codec?

A codec encodes a data stream or signal for transmission, storage or encryption, or decodes it for playback or editing. Codecs are used in videoconferencing, streaming media and video editing applications. More information here - http://en.wikipedia.org/wiki/Codec