Outlook continuous login prompt issues

I have recently took over our exchange system which i have never worked with besides creating a mailbox. I find himself having a consistent issue with a continuous login prompt with outlook 2010 and 2013. I have been setting up new laptops for users to replace their old computers were their outlook works fine (no continuous login prompt).  Users log into the laptops using their domain accounts. Setup outlook 2013 email account using the same settings from their previous working outlook 2010.

Server Settings
Server: mail.mydomain.com
Uername: first.last
Offline Settings: Use Cached exchange mode Checked
More settings: Security Tab
Encrypt data Checked
Logon network security: Negotiate authentication
Connection tab: Check connect to Microsoft Exchange using HTTP
Exchange Proxy Settings: Use this URL to connect to my proxy server for exchange
https://mail.mydomain.com
Check fast network
Check slow network
authentication: Basic

Outlook builds email then pops up a security alert regarding autodiscover.otherdomain.com with message The name on the security certificate is invalid or does not match the name of the site. Do you want to proceed?
Click yes.
Then login prompt comes up and a message to allow this website to configure first.last@otherdomain.com server settings. With https://mail.mydomain.com/autodiscover/autodiscover.xml
Check dont ask again
Click allow.
Enter login information
check remember password
Login prompt begins to constantly ask for credentials.
 
I have read some troubleshooting steps doing a Google search to no avail.
At this point Windows credential manager shows 2 accounts, One under Windows Credentials for mail.mydomain.com and the other under Generic for MS:Outlook.15.

I have deleted the domain user profile and started from scratch thinking the profile was corrupted which failed to correct the problem.

I am thinking autodiscover could be the issue.
Outlook shows its connected to exchange at the bottom but still getting the login prompt.