Can't load Movies suddenly

Suddenly I can't add a movie to a Logic song. I click add movie, locate one, and hit return and nothing appears. But strangely, the option to add a movie is now greyed out, which would suggest it is in the song somewhere. But it isn't in the inspector or anywhere on the Arrange page.

So I quit and restart the computer. Try opening an old song which contained a movie. The song loads, but Logic says it can't locate the movie it once had. I locate it manually, hit OK or choose and it doesn't appear in the song.

I need to work on a commercial in a hurry. Can anyone please help?