Have you made any mods to that script, or do you have any scripts that change it in any way?
Have you changed the font for the game, or any part of the game (especially the menus/windows)?
What's the Charset script? That sounds like it could be a candidate, as does the Glyphs and Scrunched Text bugfix scripts. I suggest you disable those, one at a time, and save/play between each one, and see if the problem goes away with one of them disabled.
It could be a combination of changing the font, along with one of those scripts. So if the problem goes away when you disable one, and you've changed the font, change it back to the default again, re-enable the script, and see if it works.