Opening file generated by earlier version

I just tried to open a file I created with an earlier version of OG.

I tried to use the “File” “Open” dialog but it refused to recognize the file as a valid OG file, even though Finder showed it as “OmniGraffle Format.”

So, I went just to Finder and double clicked to open the file (using file associations). It opened but trying to do anything caused ghost images when I was scrolling or resizing the drawing. Very odd.

I quit 7.11.5 and went back to 7.10.2 and everything worked fine.

Any thoughts as to what is going on? The last modified date on the file is 6/19 so I probably used 7.10.2 for that update. By why was 7.11.5 having so much trouble with it?`