Browser/Outlook freezes due to the login window

Problem

If I want to open the Process Portal, the browser freezes due to the login window. The same goes for Outlook when opening a task for the first time since the last Outlook restart. 

Solution

Add the fully qualified name of the FireStart server to the local intranet.

browser-outlook-freezes-due-to-the-login-window-2018-07-04