Glad to be able to help.  We were in the same boat with TAC, and due to loss of confidence, I started combing the bug tool.  

Hello- My team has seen this behavior on various trains of code and hardware platforms (9300/9200, 17.3, 17.6, 17.9, 17.12)...what we have found is that we are running in FIPS operating mode and running AES password encryption.  If we disable AES pas...

Check this bug out..    https://bst.cloudapps.cisco.com/bugsearch/bug/CSCur45606/?referring_site=bugquickviewredir   We are running 15.2(3)E1 code across our environment.  This seems to be the cause.

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCur45606/?referring_site=bugquickviewredir   doh!  only 1300 switches to upgrade...