Getting the same error. Just installed Trial Version of Outlook 2010 and noticed the message.
The error occurs when I allow Outlook to set up e-mail accounts on its own. The first try is on a encrypted connection which fails, then the option to use an unencrypted connection succeeds. The error happens during the encrypted attempts and occurs 3 times in succession.
My POP3 server just uses a password, so it seems the attempts to use a encrypted protocol is involved. But maybe someone who understands more about how it works will know what type of scenarios might generate such an error.
Also I notice if I let Outlook set up the accounts, it will succeed using the incorrect server name. Mine are pop-server instead of just pop, but Outlook sets it up anyway. But e-mail access does not generate the error even using the wrong server name.