I've encountered a problem with Firefox 4.0.1. where it only shows some letters in headlines, and other letters are missing. I've opened the same pages in other browsers (Chrome and Safari) and the pages open fine. Websites I've noticed this issue at so far: Facebook (clicking on the 'inbox' icon, the sender's name is affected), Fotolia (top navigation bar and phone number. screenshot: http://werecordings.com/images/screenshots/screen-capture-1.png ), youtube (bold text on the left in the inbox, and address book. screenshot: http://werecordings.com/images/screenshots/screen-capture.png ). Please feel free to check out the screenshots I've taken of this issue. I hope they can help. If I keep looking, I'm sure I'll find other websites with this same issue. It might be a javascript issue. I've ruled out a font issue because since I noticed this problem, I used Insider's Font Smasher 1.8.0 to clear out the font caches, then did it again through OnyX and I also used FontAgent Pro 4.140 to analyze all my fonts and then remove all damaged and incomplete fonts. Also, as I mentioned already, these same pages open up completely with no missing characters in other browsers. Please advise!