I clicked on expand track layers I found that hash marks that in indicate that some one track partially behind another track. I can see from the thumbnails that they are clearly from different parts of the video. If I clcik on either part & try to move it they both move.
I thought that some clips must have been grouped. So I right clicked on both parts but the option to group or un group is greyed out.
I have been playing around trying to see what has been happening. Your aware that if you double click anywhere on a clip the entire clip gets selected. Well I double clicked on the first picture on the problem area & it correctly selected just that one clip. But if I then double clicked on the next clip to the right I get highlighted about 6 clips to the right as well as is the first one. Its as if the first clip was both alone & in a group at the same time. I can't see what I might had done to get in this position in the first place or a very quick & easy way to fix it.
What I'll do is get the properties of each picture in the group & drag them onto the timeline & then delete the grouped pictures. I'm still puzzled as to why it happened.