Hey I just found this on hackernews, and thought I would mention it here also. If you type File:/// in native apps, and many 3rd party apps it will cause the application to crash. Textedit, spotlight, finder, safari, mail.. even iMessage. I tried sending an iMessage from my iPhone to my iMac saying File:/// it crashed the iMacs iMessage app. I also can not relaunch the messages app on the iMac as it crashes every time due to that incoming message.