Issues with PDFs not staying to scale and viewing area going wonky

[Nancy1431]

We're running Chief 12 and have recently had problems with PDFs not staying to scale as they were brought into the layout or having the selected viewing area change.  We are also experiencing the links to the folders being corrupted despite the path being defined and having checked the save in plan box.  There are 3 of us who work jointly on the same drawings and it happens most frequently when one of the other designers has been in the layout and then someone else opens it.  The 2nd attachement is a PDF of a survey that we scaled into the layout and used scaled polylines to represent the changes to the house.  Those shapes at the top of the page are no longer scaled to the pdf and were pushed up.   

 

Any ideas would be appreciated.