It looks like you have a corrupted font. Check you fonts (with the included Font Book or third party applications) and clear your font cache (with some free programs like YASU or Onyx).
Maybe you should run all the cleaning routines and let the program reboot your Mac. I say one the program reboots your Mac that you immediately manually reboot again to completely rebuild your startup/shutdown cache.
Over all this problem of your is a classic corrupted font.
Mac Pro Dual 2.8 Quad (2nd gen), 14G Ram, Two DVD-RW Drives, OS X 10.8.3
2006 Mac Book Pro 2.16 (first Gen) OS X 10.7.4
2TB Time Capsule, 2 TB
32G iPhone 4S Black, iPad (3rd Gen) 32G Black