Lync 2013 credentials problems on domain computers

Question

Hi folks,
We are having trouble with Lync 2013 and credentials on our domain computers. We have been using Office 365 and Outlook for our email for a couple years and it has worked well enough, so recently we decided we wanted to start using Lync as well. We deployed
the Office 365 Pro Plus suite available to us through our Office 365 subscription and signed in. The first sign-in went as expected. It asked for a username and password, asks if it should remember those credentials for next sign-in (yes), then connects and
everything with Lync itself functioned normally. Subsequent sign-ins have not been normal.
When a user restarts their computer and launches Lync it remembers their user name but not their password. Once they type their password in it asks if it should remember those credentials for next sign-in again, then connects. If a user exits and re-launches
Lync without restarting it remembers their credentials and signs in properly, but then immediately a popup box appears saying that "Credentials are required" in order for Lync to get calendar information from Outlook ( http://i.imgur.com/hqcK426.png
We know the problem is only happening with computers on our domain, but we don't know why. I tested things out on my home desktop and network by installing Office 365 Pro Plus, setting up Outlook, and then Lync. Both Outlook and Lync auto-discovered everything
normally after getting my credentials and Lync behaves as expected every time the program launches. I then brought my personal laptop in and tried the same thing on my work network to see if it is network related, but Lync behaves normally on that computer
as well.
I originally worked on the problem at the Office 365 Community Forums ( http://community.office365.com/en-us/f/166/t/246014.aspx ), but after we isolated the problem to something with the domain computes I was told that they could not help me any further
and was referred here. Does anyone have any ideas as to what is keeping Lync from behaving properly on our domain computers? We have a mix of Windows 7 x64 and Windows 8.1 x64 computers, all joined to the same domain and with the same basic suite of software.
Thanks,
~Misharum
PS: How do I verify my account? The outlook.com email address has been verified, but I don't see anywhere to do verification in my TechNet profile here.

Answer 1

Yeah, the clients are fully patched. I put a support ticket in through Office 365 and the rep there was able to help me. It ended up being two separate problems.
Lync was not remembering my credentials to automatically log me in between restarts:
Installed the latest version of the Microsoft Online Services Sign-In Assistant.
After signing signing into Lync another popup appeared asking for credentials again to access calendar information. (two steps to solve this one).
In Active Directory Users and Computers, open up the properties of each affected user, go to the Attribute Editor tab, find and double click the proxyAddress attribute, and add in
sip:[email protected] where the userid is the user's login name and domain.com is your domain. I'd imagine this is scriptable in PowerShell but I don't know enough to do it.
Then on the computer that the users will be using, while the user is logged in, add a dword of NoDomainUser = 1 in the registry at HKCU\Software\Microsoft\Office\15.0\Common\Identity. The most sensible way to do this in my mind is with a group policy so
it will get written to each user's registry under their profile when they log in.
After doing all of this Lync remembered my credentials between restarts, signed me in automatically, and only gave that credentials popup on the first sign-in after applying both changes in step 2.