Font Finagler can help troubleshoot misbehaving fonts.

If you’re having problems on your system with text appearing “garbled” as in the sample image above, it could be caused by corrupt font cache files. What appears to be happening is that incorrect or corrupted encoding vector information is being used when mapping the character codes as input by your keyboard to the glyphs they represent in the problematic font. You can run Font Cache Cleaner to purge these cache files in an attempt to restore normal behavior. If you use Font Cache Cleaner but the problem remains, then it could be caused by a font conflict or by a corrupt font. Try removing fonts to isolate the problematic fonts that are causing this behavior.