When an application bumps into BeOS’s memory protection scheme or commits some other offense, a message pops up telling you that an error occured and that the program will be shut down. OK?
Not OK! Don’t click that button right away! Sometimes the program in question will be completely non-functional, and you might as well kill it. Other times, only one non-critical thread of the program has crashed, and you can keep working in the rest of the application.
For example, you can save changes in any still-functioning windows before killing your word processor or graphics app. If the Tracker crashes, and you don’t have a Terminal open, you should launch it before you kill the Tracker, because afterwards you wont be able to! And if you get one of those rare messages telling you that the app_server has goofed up, ignore it and start shutting down your computer and rebooting.