A number of problems are all related to this same issue:
All versions of Notification Server
There are several causes:
When a password change is to occur, it is best to anticipate this and modify the application identity password before the password is changed for that account throughout the domain or workgroup environment. In this case, the best practice is to modify the password in the Notification Server's Application Identity settings prior to changing the password on the computer or in the domain. If done at nearly the same time and in that order, any resulting problems can be prevented.
If the password is not changed on the Notification Server before changing it in the environment, the Notification Server console cannot be accessed. When this occurs there are two options:
NOTE: If you encounter an error while attempting to change the Application ID, see KB HOWTO10267.