When attempting to add items to the trusted email addresses and trusted domains for select users, instead of the popup box appearing, the browser bogs down and stops responding.  The users in question do not have huge preexisting lists. They have maybe 5 or 10 items in each list.  I see this happen in Chrome, IE, and Firefox on both Windows 7 and 10.  On the same system, I can go to my own trusted senders lists and they open just fine. It appears that there is some sort of corruption with the lists of the users in question.