Can't authenticate locally to new POP3 and IMAP on Exchange 2003

I'm in the process of finalizing standing up our first Exchange 2003 server.  Most everything is working properly.  OWA and OMA work (through the firewall).  I cannot seem to get RPC over HTTP to work.  Also, I've gotten some iPhone and Blackberry users asking me to get them back online.  I've started the POP and IMAP services.  When I try to connect to them using Outlook 2003, even from within the network, I cannot seem to authenticate.  Every combination of credentials that I provide do not work.  Furthermore, when I telnet to POP and try to login, I'm being told '-ERR Logon failure: unknown user name or bad password.'  I'm pretty sure I know my own username and password.  I've tried various versions of usernames: windows_username; windows_domain\windows_username; exchange_alias; windows_domain\exchange_alias.  Everything gives me the same response.  I've tried messing with the authentication settings in ESM with no success (do you have to Stop and Start the POP or IMAP services after making a change to them).  I'm starting to think that I have some common authentication problem with the RPC over HTTP setup because it won't work from within the network also.  I'm not using SSL or anything fancy.  I just want it to work before I start tweaking security.  Any advice you would provide would be much appreciated.  Thanks.