Thank you for your post.
Is the same Print Setup being used for all printing? Or, do you have scripts with Print Setup being called several times? Have you tried creating a script with the Print Setup and Print steps, and then when you need to print, reference that script? Do you notice if this printing change occurs with a specific file? specific layout? Any other information you can provide may be helpful.
No script is used for printing, all done through the Print dialog box manually. Choosing All Pages and Current File and Print. Also, I should mention that even after it prints incorrectly, when you choose Page Setup again, the proper printer is still selected. So I don't have to re-select the printer. I just open the Page Setup dialog box, click OK, and then it prints correctly.
I just experimented to see if I can replicate the problem. I printed the same record, same layout, 4 times in a row, worked fine. Switched to another layout, same record, printed fine. Switched to a third layout and ran a script, came back to the first layout, and it then printed incorrectly. So I looked at the script and noted that it did have a Page Setup/restore step, so I deleted that and tried again. This time everything printed fine.
But again, it seems random, so I will continue to observe and report back if it happens again. Perhaps that Page Setup step was messing it up. As I mentioned, it's worked without a hitch for 18 years, and this only started once we switched to Lion and v.11. Nothing was altered in the database, same printer, etc.