Try opening the file on the Mac system, enter layout mode and then see if changing the font settings for the layout make a difference.
Thank you for your suggestion, but it did not work. I switched to layout mode and highlighted the field, tried to change to a different color...and nothing. Anyone have any other ideas? If not:
Is the upgrade from 7 to 12 pretty seemless? Would I have to redo any tables, relationships, layouts, etc.?
Don't change the color, change the font. Fonts are named as times, arial, etc. There's a known issue with fonts on some Mac systems that's fairly easy to correct. If selecting a different font solves the problem, this is a strong indicator that you may have an extra or damaged font suitcase on the mac system that needs to be removed.