Nesting, quick explanation.
If you create a project and save as “Movie One”
Then create another calling it “Movie Two”, with this open in the timeline it is possible to insert Movie One, this is literally adding a project inside another, Known as nesting. The project file shows as a single clip similar to viewing any other video file.
If you now open “Movie One” and edit, delete clips etc this will affect “Movie Two”
If you are unsure about nesting then it can be easy to do without knowing.
Jpeg images, some problems when using Progressive types, this is the way the image has been saves/created, generally Jpegs are Baseline. (right click image and select properties, Jpeg tab)
Downloading video files, yes these can also cause problems, there are thousands of video types, many using non-standard sizes. Some types will cause problems for Video Studio. Using files from a camera are the safest types.
Mpeg4 and Mov types require QuickTime, As you are having crashes I would recommend installing an earlier version, 7.5.5, and just to contradict myself , if you cannot open Mpeg4 types then install the latest version of QT!
You seem to be using quite a variety of clips, any one may cause problems, unfortunately difficult to identify.
Having said all that you are using VS11 on Windows 7, not an ideal combination!!!!!!
Download the trial of X4,
Note that project files created in X4 cannot be opened in VS11.
Use VS11 to create a copy of your project to be used in X4.