Had to System Restore for unknown reasons. Symptoms were loss of desktop icons and Start Menu Box. Nevertheless, the restore worked fine, but resulted in the old "nasty" login failure messages. Just would not go away, and I have had experience with these before.
I remembered a prior solution where, I opened my Yahoo Email (which worked!) then just left it open. Sure enough, overnight and perhaps 12 hrs or so, the Outlook login failure message was gone and my inbox had caught up on my incoming messages.
Did the System Restore trigger the Outlook login failure? These episodes are like a bad cold, once recovered you just want to forget all about it. Any tips for next time?