Photos and iPhoto videos not available to iMovie.

I have been using iMovie 9.0.9. I had created a Movie using stills from iPhoto as Titles and then edited a movie which had been down loaded into iPhotos (videos downloaded from my 'Bloggie' SD card always went into iPhotos). This movie appeared in iMovie/Event Library under iPhoto Videos. After several months I now want to transfer this movie to iDVD. It is all visible in the Project Library and the Titles with backing music play fine, but the video displays 'Source Clip is missing. I have now opened iPhotos and 'iPhoto Videos' appears in the Event Library in iMovie, but the project videos still display Source Clip is missing. (There are no editing marks in the project video). Do I have to completely re-edit the movie?

I have looked back at some of my previous projects and they appear to be missing either titles or backing music as well. Help.