The server for xxxxx returned the error 'Logon failure: unknown user name or bad password.' Your username/password or security settings may be incorrect. Would you like to try re-entering your password?

This happens generally when i leave the machine and the screensaver starts, or when I open Outlook for the first time each day.

If I select 'Yes', the machine refuses my passwords, if I select 'No' the machine starts fetching emails again as if nothing has happened.

Clearly there isn't a problem with the names, passwords or security settings. This is another issue

I have set up the accounts in every possible way according to the various instructions and other information from other people's problems.

My Exchange account is not affected.

This is beginning to make me mad. Every time I leave the machine for more than a few minutes I have to clear the error messages on three email accounts.