Just upgraded the wife’s Mac to Firefox 3, seemed to be painless and straightforward. Until she went to use it the first time herself and some sites would show garbled text, what looked like squished fractions for certain text on web pages. Only certain sites, only certain text. Wikipedia is one that is usually affected.
Unfortunately not much information can be found on MozillaZine or most support forums. Mainly because it’s kind of hard to describe or find the right search terms for. But I did find a support post finally that pointed me to the true fix: disable the Helvetica Fractions font in Font Book.
Hope this helps save an hour of someone else’s time 
Yeah, I had solved the fractions issue, but I still have the same problem with other sites. Some people have told me its a preferences issue, some have told me its a font issue… but I don’t seem to be getting any solutions to it… It’s quite frustrating.
Thanks for your link on fixing this problem. I was tearing my hair out with this one, and your discovery of the fix to remove Helvetica Fractions worked like a charm!!!
THank you thank you thank you!
I also have the problem what Tom is describing. If you look at http://www.WendyTokunaga.com on Safari, the Zapf Dingbats with red circle comes through. So do in Windows. It even works OK on FF 2 but not on FF3. It shows letter “l” and not seeing the Zapf Dingbat at all! No solution yet.
Thank you ever so much for this fix. This saved me from a lot of wasted time and frustration.
thanks it fixed the problem! (firefox 3.0.3, mac os x)
Thank you so much! I have been tearing my hair out for months!