It's funny, however long you spend fixing problems, there are still new challenges lurking! This one I have never met before...Outlook repeatedly asks the user to type their password. It accepts it when it is typed, and fetches and sends emails, but next time it asks again...and again!!!
None of the obvious fixes worked - checking the password in the account settings, making sure that it was set to remember the password, creating a new Outlook profile. The answer is pointed out on the Microsoft support site, and involves deleting the registry subkey for the "Protected Storage System Provider". Doing this effectively deletes all the stored passwords for this user account. Once re-entered, this user's system then started to behave again!
