You won't like this answer, but it is likely the correct answer.
If Outlook all of a sudden keeps asking you for your password when automatically checking email (even though you checked 'save', nothing's changed, and it still keeps asking), it is likely because your ISP has an issue, and you will just need to wait it out and suffer through the Yes, Yes, Yes.
Eventually (it has taken a week sometimes for mine to work itself out, but generally only a day or two) it just starts working again without your doing anything.
If you really, really want to waste a LOT of time and muck around with something, you will find instructions on how to create/replace Outlook email profiles, change your registery, etc. etc., but trust me, it will work itself out. When this happens I just close Outlook more frequently until the ISP gets their act together.
For reference, mine was @yahoo.com, but it could be any.
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