Thanks for sending the vizx document file. By looking at the end of the file in a text editor, it's obvious that the file has been truncated. This can happen if you are saving a document to a remote folder and the internet goes down midway through the save operation. Loading a document with this problem will cause the error you've observed.
In most cases, it will not be possible to fix this file. You can however go back to the last previously saved file. Delete or rename the vizx file that you are having problems loading. Now look for a file in the same folder with the same file name and ".old" added on as a new extension. Rename the file by removing the ".old" extension. This file will contain the contents of the project from the last time you saved the file.
