Movie Maker does not behave like it is demonstrated to do

I want to chop off part of the start and end of my movie and keep the part in the middle.

Everything I read says that you should be able to see the frames on the right and the movie with time slider on the left.

My problem is that when I  load my movie the left bears no relationship to the right making it impossible to select the trim frames.

In fact the frame (or any frame around it) does not even appear on the right. In fact all the right frames look much the same.

Thanks, see this image which explains it all:   (using Windows 7 64 bit)