A few days ago, I tried to install a new font for LaTeX from an OTF-file. I used the script otfinst.py, by John Owens. However, when I decided not to use the font after all, none of the regular LaTeX fonts (Computer Modern, by Knuth for example) seemed to work any more, everything was replaced by an ugly sans serif font.
Thinking I must have messed up LaTeX, I set out to reinstall and undo all the
changes I made. This was actually not the case; after searching the web a bit I
found that sometimes the font cache would get corrupted. To interact with the
font cache in Leopard (Mac OS X 10.5), one uses the atsutil command:
atsutil databases -removeUser # clears the cache
atsutil server -shutdown # restart the ATS server
atsutil server -ping # see when the server is back up again
You might want to issue the first command as root to clear the cache of all users.
Be sure to restart any running programs such as Safari and Preview, or you will still see weird fonts.
See this article on Macworld for more information.