Getting intermittent "Invalid Credentials (Failure)" message from IMAP server

Getting intermittent "Invalid Credentials (Failure)" message from IMAP server

I've been receiving intermittent IMAP login credential failures using Outlook 2007 and Mail on the IPhone. Doing a refresh and/or terminating the client and restarting allows things to work for awhile but then the login failure appears again. Anyone else experiencing this problem? Started at around 12:30PM NY time.