Here's a little hint:

In the last several months, Some of my e-mails and web pages have contained random lines of type that show up in "Greek" or at least in symbols that contained odd letters. Basically making text unreadable. Through the Apple support forums I found out I wasn't alone. There's a conflict that happens if you have Helvetica Fractions or Times Phonetic typefaces open on your Mac. I closed those for my everyday use and will just reopen them if I have a design project that requires them. (By the way, I use Suitcase Fusion to manage fonts.)