However, I still cannot get the Print Setup or the Page setup to stay on A3. My printer is setup as Epson 1160 which is A3, although when you view the changes in diagram/properties the page size is shown as changed. Click on File/Page setup and it shows A4. puzzled.
With this I would expect the grid lines to change on the diagram to represent the new A3 size, but it does not move. 
Any ideas,
Sam
Sam,
I noticed something similar today...

Exit EA.
Next, go to the printer from the start menu, set the default preferences to A3. (set printer to default, if you have others)
Next start up EA, check the page setup. The printer should be the 1160, size and orientation as you want. If not, let us know, and reset to your desired values.
Next go to Tools|Options|Diagram - check the Default Page size. Reset if not what desired.
Exit EA, restart EA. Check nothing has changed.
Create a new diagram - Check settings are those desired.
Pick existing diagram - Reset the pagination as desired.
Exit EA, restart EA - check the settings on the two diagrams haven't changed.
You now have reproducibility and stability - consistency (that word again!)
If the above Test fails at any step, let us know...
HTH,
Paolo