Vielleicht mal den Fontcache leeren

How to remove Font Cache files directly in OS X (Panther):

First, launch the Terminal (found in /Applications/Utilities). These instructions are CASE SENSTIVE. This means that UPPERCASE and lowercase are important to remember. In the Darwin environment of Mac OS X, two files can be named identically but be different files if the case of the filename is different, (i.e., 'FILENAME' and 'FileName' would be two different files.)

After each command be sure to press Return. These instructions assume that you are an Admin user in OS X. If you are not, or this is a shared use machine, please contact your administrator for assistance. This is usually easiest if you copy and paste each of the commands to type. If you receive a "No Match" or "File not Found" error, continue on, not everyone will have all of these files in all locations.

You'll be presented with a prompt similar to:
Welcome to Darwin!
[hostname:~] username$
At the $ prompt type the following (followed by Return): cd ~/Library/Caches. The prompt should change and say:
[hostname:~/Library/Caches] username$
Next, at the $prompt type in: sudo rm *.fcache*. You should be prompted for a password. Go ahead and enter your password followed by Return. You'll be presented with the prompt if it was successful. Next, at the $prompt, type in: sudo rm *.FODB* and sudo rm *fontcache*. Now at the $prompt type in cd /Library/Caches; the prompt should change and say:
[hostname:/Library/Caches] username$
Again, type in: sudo rm *.fcache*, also sudo rm *.FODB* and sudo rm *fontcache*. Now, our last stop for cache files: cd /System/Library/Caches. The prompt should change and say:
[hostname:/System/Library/Caches] username$
Now type in sudo rm *.fcache* and of course sudo rm *.FODB* and the last file to remove sudo rm fontTablesAnnex*. Now you can select 'Quit' from the Terminal menu and restart your computer.

normalerweise sopllte es genügen in den SafeMode zu starten, da wird auch der Fontcache gelöscht.
http://support.apple.com/kb/HT1564

Für mich sieht's nach einem Fehler der Systemschrift "Lucida Grande" aus.
Also ist möglicherweise der Font selbst defekt, du hast sie versehentlich deaktiviert oder es besteht ein Konflikt mit einer anderen Schrift. Vielleicht erstmal in "Schriftensammlung" nachschauen und den Font überprüfen lassen (Ablage Schrift überprüfen, bzw. Rechtsklick)