While password update in BM getting 'insufficient privilege' error only on some user id's. Why?

In future we are planning to move from single sign on to standalone for accessing Demantra application (7.3.1.4). In the process we are updating the passwords in BM and getting 'insufficient privilege' only on some user id's.

Tried to delete the user and I am got the same error 'insufficient privilege'. I clicked OK and interestingly when I checked the user has been deleted from BM. I recreated the user. Could not log in so I had to bounce the app server and was able to log into the application. I tried updating the password and I got the same error 'insufficient privilege'.