Not sure what the problem is (naturally)

I have just started using Movie Maker to edit and then save recorded TV and radio to remove adverts, announcements, etc.

The first time I opened a file to edit, Movie Maker analysed it for a minute or two and then showed the full 35 minute programme recording.  I edited front and back and then saved the audio (it was a radio programme recorded through Windows Media Center) to mp3 and it seems to have saved it perfectly.

I then began a new project and selected the next programme to edit, and Movie Maker simply opened a file of 7 seconds length with no audio or video attached.  Even if I open the original file that opened first time, I still get the same 7 second file.  The software doesn't go through the analysing process that it did on the first edit.

I am at a loss, and would greatly appreciate some assistance to sort this problem out.

Regards

Jamie Murray