Rename your configuration file and see if that fixes the problem. If not, then we'll need more information if you want help. (Such as operating system, game version, video card, driver version, and a screenshot of the problem)
"In addition to knowing the secrets of the Universe, I can assure you that I am also quite potty trained." -Koenma (Yu Yu Hakusho)
In case the default configuration file (generated when you rename/remove your current file) still causes this issue, try to add the following line into your configuration file:
This disables font rendering via texture meachanism. Even if this is working for you, I can't tell you why this issue appeared on your system...*shrug*