I have no idea what this means. I did delete a font recently, using Linotype Font Explorer, but it wasn't an important one. This message appears in two boxes at once, one over the other. I used the web for a while and then the message(s) appeared again:
A problem has been detected with the font OTS derivied font, in the font file $C. The system will attempt to disable this font, but to avoid future problems, you should quit all of your open applications and remove this font file or replace it with a new version.Try here:
http://www.nybooks.com/articles/archives/1987/jul/16/on-r-langton-douglas/
