Jason Miller had problems opening JPEG files in JPEGView 3.3.1 and Graphic Converter 2.9.1. "Every time I would try to open a JPEG file, my system would freeze." Trashing QuickTime Preferences (and possibly reinstalling the QuickTime software as well) solved the problem..
Gordon Webster found that "every time I loaded a diskette or CD ROM, the Finder would quit and restart." Once again, deleting the QuickTime Preferences file (as well as reinstalling the QuickTime Settings control panel) solved the problem.