Last November I put it on my IT wishlist for this year. So I am hoping to get a copy to play around with soon. It oes look intersting for visualization.
First, try to save to multiple locations - is there something wrong with where you're trying to save the document? Try "Save As" and see if you can rename. If you're saving to a network drive there can be issues. The file is not "Untitled" so you've saved before, and maybe it looks like a file system issue.
