VISTA Ultimate/IE8/Outlook 2007-Cannot verify security cert

Beginning on March 19, 2009, when I start Outlook (which is pointing to my AOL email account), I am getting an error:"The server you are connected to is using a certificate that cannot be verified. The target principal name is incorrect." When I click into the error message I see certificate is issued to imap.aol.com. This is valid from 3/19/2009 thru 3/19/2011. Prior to March 19, I did not get this error and I have made no changes to IE, Vista or Outlook other than for updates that may have come from MS Update.