Adobe Illustrator CS2 for Mac Keeps Crashing

A user has reported a strange problem about Adobe Illustrator CS2 on a PowerMac G5 running Leopard. It started about two weeks ago and whenever he tries to run Illustrator, the splash screen appears and then it crashes without any error message.

I checked the logs and crash reports. I didn’t find anything related to the crashes. I then tried to run Illustrator by myself and I found that it crashes right before it tries to build font menu. With this information in mind, I opened up Font Book in Applications and validated the font (File -> Validate Font). About 50 duplicate fonts were found. The crashing problem is gone after the duplicate fonts were deleted.