Sounds like you have some files missing. Reinstalling the theme might help. Or the fonts. You can try something like Code: root apt-get update apt-get install --reinstall hildon-theme-alpha (assuming that's what you are using, substitute as necessary) On the other hand, you might have a file system corruption. There have been plethora cases like that discussed here (the forum, not the thread), just do a search.
root apt-get update apt-get install --reinstall hildon-theme-alpha (assuming that's what you are using, substitute as necessary)