just to isolite one possible problem: Could You try to change the font?
Apparently Arial isn't a good font anymore. I guess Helvetica is better.
Is there any list of "better" fonts to use for cross-platform FMP solutions?
Lion and Snow Leopard Systems have font issues that your older system does not. Changing the font is the perfect test here to confirm that issue. Typically, it's caused by having two font suitcases for the same font in different parts of your system as I recall.
You should be able to find and remove the offending font suitcase and then arial will work correctly for you. I'm not a Mac user so I am repeating what I can recall from posts made here. You may need to research "Snow Leopard Font" here to get a thread with a more detailed description of what you need to do.