Issues with ALM Explorer 12.53

1. Multiple authentication. When the SiteAdmin(LDAP Enabled) page is accessed, we are initially prompted with “Web Server Authentication.” Once we finish this step, we get prompted for “Proxy Authentication.” After completing this we are directed to the log in portal of the website with a prompt "External Exception C015000F". If we close this and enter our Active Directory username and password, we are able to log in to the application. Is there a way to avoid these multiple authentications? Also, “Save TD Connection Settings” also does not work upon closing the browser.
2. Slowness in log in and log out. We have to wait more than minute to log in. Log out seems to be faster upon changing few security setting. But the slowness in log in still persists

System Info:

ALM: version 12.53, installed on Microsoft Windows Server 2012 R2, OS: Windows 7 ENT

Greatly appreciate your input.

Thanks