I'm making a video in movie maker and have been using the split tool to delete out sections of unwanted video successfully.  When I got near the end of the video I clicked the split button and it made the timeline/storyboard and video preview disappear and I am not able to split anymore.  I can click the undo button and get everything back, but I can't split anymore.  What happened?  How to fix it?  Here is a quick screencast video showing what happens, http://screencast.com/t/rRERI9XS.  The problem started after I copied a clip and pasted it in the timeline and then added 2 or 3 captions.