If you putting together a video on the timeline, and Studio 11-14 locks up, the portion of the timeline that it was rendering when it locked up, gets corrupted(flickers/skips/black question mark, during preview).  Currently, if you find a portion/segment of the timeline that does not preview correctly, you have to make a minor change to that clip/transition/title to make it re-render that portion or segment.  The only other option is to delete all the projects temporary files, then re-render the entire project. 

It would be nice if you could just right click on the clip/transition/title, and select re-render.