http://adobeforums.com/webx?14@@.3bc39c4b/3Seems to be caused by incorrectly installed fonts, mainly on Vista systems.
This seems like a good place to start.
post form link above wrote:
I had the same problem running XP Pro with 2Gb of RAM. Here is how I fixed it.
First remove all of the fonts that were installed by Photoshop. These fonts will all bare the date that you installed PS. You can do this by simply dragging them out of your fonts folder (Windows) into another folder. Then (I did all of this w/o restarting PS) place some text in an image - everything should work fine. Next, copy all of the fonts back into the installed fonts directory. Select the text that you place previously and then click in the drop-down box that allows you to select the font. Keep pressing your down arrow to cycle through the fonts until you receive the error message again. When you get the error message you have discovered the problem font. Remove it from your fonts directory and you will be good to go.