Today I ran into a very frustrating problem: whenever I would start the android emulator, either through Eclipse or the command line, it would crash, with no helpful messages. When running through Eclipse, it simply crashes and shows you apple's "This application has quit unexpectedly" message. In the command line, you see that a segmentation fault occurs.
Well, it turns out that this is a known problem, and happens when a USB headset is plugged in (debugging nightmare right?). This can be fixed if you either unplug the headset, or change the sound line-in back to the default (not the headset). From command line, you can run the emulator with the no audio option:
$ emulator -avd MyAvd -noaudio
Even with google searching it took me a while to track down such a vague problem, so hopefully this will save someone the couple of hours I spent trying to debug this ridiculous problem.