Outlook connection issue/failure

My workstations on my domain are running pop mail in outlook 2003. Im running 2011 SBS / Exchange. I recently added mailbox accounts to the 2003 outlook clients to prepare for the use of my exchange server. Now, whenever I open outlook on some of the client pc's, I get a window that says "Connect To "local computer name". It;s looking for a user name and a password. It also has a check box to remember the password. I'm not sure what this is asking me. Iv entered every username and password that I can imagine that it would be but it just comes right back. Searching for a solution is also diffucult because I'm not sure what type of issue this is. Any info would be greatly appreciated. I have also upgraded outlook up to 2010. Also, whenever I remove the exchange connector in outlook, the problem goes away. Additional information. I discovered that when I look at the SBSserver console and look under users and groups tab, I seel a list of users. However, the last two users do not have an email listed so this is mostlikely why the connection error. Now I need to know why those last two users I created in the same manner I created all of the users failed to create email addresses. Could it be because the last two users are number 11 and 12? Could this be a license issue and I'll need to increase the number of user licenses for the server??