I'm sure most of you have noticed when you press Alt+F4 while in an MS Office window, or click the X button in the upper right window of an Office document, it tries to close all instances of that Office application.  If you have a number of word documents opened and you just want to close one of the documents, you accidentally clicked the window close button (X) of the Word window and since you are in a hurry, you clicked No for all the dialogs.  You did not notice that the next prompt was "do you want to save the other document", data lost, :p.

To be cautious i always read these dialog boxes and if i'm not sure what the hell he is saying (to be honest, i still don't know one of the prompts it tells me when i try to open the same document or a document with the same name), there's always a Cancel button, hehehe.  For the keyboard junkies out there, if you want to close just a document instance, use Ctrl+F4 [EDIT] or Ctrl+W (non-VS shortcut)[/EDIT]instead, just like closing a tab in firefox or in visual studio.