For the third time in a year and a half I was unable to open Outlook getting a message that my identity needed to be rebuilt. 
The rebuild failed and I had to piece together various methods gleaned from these forums and elsewhere on the net to get a semblance of recovery. 
My question is: What causes this Identity corruption? What can I do to avoid it? 
I have seen many work arounds to fix but nothing to indicate a cause.  
Thanks