That’s an incredibly long thread (some 42 pages of stuff). The short version is more or less:
Don’t open files into PPT from DropBox, OneDrive or any other similar locations. Copy them to your hard drive, in a folder that is NOT synched, and open/save there.
Apply available updates to PowerPoint. You don’t mention which version of PPT you have; specific instructions for this will vary. MS may not have totally eliminated this problem, but they’ve definitely got it on the run.
Another from microsoft:
It would be helpful if you can upload a sample file (images / word doc on a common FTP site like sky drive) so that we can test the same.
After reading through your post, I feel that the cause of the issue might be file corruption (Document / images that are inserted)
From where do you copy the picture and paste?
Create a local copy of the picture and save it on the computer; try inserting the image in the other word document and check if the issue persists.