title: missing source files
body: <h2>This is NOT a life or death issue. I do have a backup from 2 or 3 days ago. - I think the answer to this may be "Learn to always save &amp; backup your files every night, before you turn out the lights and go home" but just in case there is a happier answer, here goes.</h2>
  
  <p>I was programing some Android/Java stuff in Eclipse. I left the machine on with eclipse open and a couple of source java/xml files open inside of eclipse and gave up for the night. When I sat down at the machine this morning, I had a message that windows had preformed an update, and had re-booted my machine. after re-logging in and opening Eclipse it showed the source files in edit windows and they looked normal, but as soon as I tried to type in the edit window, I got some kind of a message that "Files are derived, do I really want to edit them" (I could be wrong on the exact wording. I didn't copy the text down before hitting no or Cancel or whatever the choice was that I thought would get me out of there without doing anything). after I left that screen, it showed me a now blank edit window for the source files. I closed that and and tried to re-open the file from the Package Explorer, but it wouldn't open. So I closed Eclipse and took a look in the /src directory and it appears the source files are gone. I do have a backup from a couple of days ago, so it's not a life or death problem to go back, but my real questions are. 
  1- Is this a normal occurrence when a machine boots/power fails/crashes unexpectedly with source files open in Eclipse?
  2 - Did I answer the "Files are derived..." question wrong? is there something I could have done at that point to rescue the file?
  Any comments welcome. - Joe</p>