Attention Mac OS X Users!
SAVING you work frequently is something we should all get in the habit of doing, but we’re all human and sometimes we forget. It’s only when you’re really busy doing something that you tend to forget to save quite as often as you should, and without warning Photoshop will throw a fit and close.
It can be quite demoralising to have that screen pop up telling you that photoshop has quit unexpectedly, especially when you haven’t saved for a good hour or more.
If this has ever happened to you then you'll want to install a free application called EverSave: http://www.tool-forcesw.com/eversave/