I downloaded some fun fonts (possibly a bad idea) and installed them. Some of them had an invalid font name table. One of them (a Metallica styled one) seems to have taken over as the default for anything involving JavaScript in Safari (a different font has taken over in Firefox, but I'm not sure which.) After I first noticed this, I first deactivated it in Font Book, when that didn't help, I deleted it entirely. That also didn't help. I'm now unable to read any text presented by Javascript in Safari. Does anyone know where I can change the default font for Javascript, or delete whatever copy is hanging around my system?