Error on Saving: There was an error generating the XML document.

I have just experienced the same exact behavior including the disappearance of the images on the slides (they still appear in the thumbnails and timeline).  The only difference is that I am using Storyline 360.  I deleted two XML files from the temporary folders.  There was hardly anything else in there.  I also use Dropbox but attempted to try and save locally to no avail.

Was there any progress or solution on the issue above that can be shared?

Thanks!