Case in the corner series: The crashing Add User Wizard
Case in the corner series: The crashing Add User Wizard – The Official SBS Blog – Site Home – TechNet Blogs:
“This was a very strange situation, the most likely cause was that the original Default Policy had been manually renamed to the Windows SBS Email Address Policy and a subsequent service pack for Exchange tried to recreate the missing Default Policy or it could have been as simple as some incorrect manipulation of AD objects..”
The lesson to that blog post, besides calling in support when you need it, is to not muck around with the default policies and settings. They are there for a reason.