Multiple users losing the Section data in their profile

It appears that the profiles for most of our Lead section (though not all) somehow lost the value of their Section parameter.  It was all correct previously.  I’ve checked the permissions and only Site Admins have the authority to change other users profile info.  I checked with the other Site Admins and none of us has made any mass changes to the Lead section. 
Since it is so many users, it's highly unlikely that that many users all made an accidental change themselves.  Has anyone else seen this sort of thing?  Any idea how this might have happened?
Jeff Aldrich
Great Northern Union Tech Guy