Can't get email - msg is Mobileme IMAP Server Failed

This is a strange problem. I have multiple Apple devices, Iphones and Macbooks. I have multiple .me email addresses accessed via all the devices. I recently upgraded to ICloud. One of the Macbooks cannot update to ICloud. So I turned off mobileme on that computer. It is able properly access all of the .me accounts but the main one? So I removed that account in mail preferences and tried to reset it up. I get the following message: Logging in to MobileMe IMAP server "mail.me.com" failed. Make sure the user name and password ou entered are correct, then click continue..." If you continue it sets up the account but it still cannot access the email? I have confirmed that I have the correct username, email address and password on the other computer. Also, the other .me accounts all work just fine on both computers? BTW, the computer where the email is not working is running IOS 10.6.8 Any ideas about how to resolve this problem? Thank you in advance for your help!!!