More Problems With Movie Maker 6.0

I recently prepared several small projects for my friend (who has a digital camera but not a computer).  I played them back and they were fine so I invited her to visit in order to O.K. them before publishing and getting avi files.  To my consternation when I opened the projects, all that was there were the titles and transitions.  All the pictures and video clips forming the project had crosses on them and the error message came up that Movie Maker cannot find the file.  I have checked and they are all definitely still on my computer so what has gone wrong?