CODEC Problem importing MPG to MS Windows movie maker

I have tried to import a MPG file recorded using a gismo to pick up HDTV on the laptop.

I keep getting a message:
The file \PEPS Parra Eeels 2009-9 Edited.mpg cannot be imported because the codec required to play the file is not installed on your computer. If you have already tried to download and install the codec, close and restart Windows Movie Maker, and then try to import the file again.

Any help will be appreciated before I go crackers

Download and run gspot against the file
http://www.headbands.com/gspot
then report back what it says about the container (file format), video codec, and audio codec.