Downtime due to a bad font
Well, that will teach me not to use a beta version of a font. I just had a spate of crashes due to an invalid font file.
Of course, it wasn't completely corrupt, so it worked most of the time. And I get enough hits that I took me forever to figure out exactly which font was at fault: The server logs and stack dumps were pretty much useless. Even printf's didn't help, since the threading confuses everything. I finally figured it out via old-fashioned process of elimination.
File Formats: TTF