Only character "Da" not displaying correctly

[j25463233]

I like to listen to the podcasts right in iTunes on my computer. I like following along with the notes in the "podcast information" window. Although, there is an unusual problem, only the hiragana character for "Da" does not display properly. It shows up as a question mark inside a black diamond.

I realize this may be an encoding problem, but it's only happening for that ONE character!!!!!!!!!! Any ideas on what's happening here?

[j25463233]

Ok, just noticed that it only happens with the early lessons. It stopped happening around the end of March 2006. I didn't realize because I'm listening to all of the lessons from the beginning. Now I know it must have been the text coming from the podcast was causing the display problem and not that my computer didn't have the character in my font library or something.