Chloe, I agree it's a long thread, let me address your 4 summary statements:
1. Issue started after the April WSUS update cycle, affects ALL Office apps, but manifested differently (Outlook gave Proxy login window, other apps showed SSL error). Wireshark showed 4 outgoing requests to 'office14client.microsoft.com' which is
ultimately what we wish to stop. We don't have a problem accessing the Internet at need, the problem is we don't want Office trying to do it
on it's own!
2. After changing reg keys, Proxy login now shows for all Office apps including Outlook, so at least it's more consistent behaviour, but Wireshark still shows the
unwanted outgoing packets to the URL.
3. I am a network/systems admin at a customer site, all investigation/troubleshooting have been on a workstation in our Development system so as not to affect Production users.
4. Every change so far has not altered the basic behaviour: for each app opened, some popup box appears, 4 times, one at a time. So you get it 4 times for Outlook, 4 times for PowerPoint, 4 times for Excel, etc. When you close all 4 boxes for
that app, you don't see them any other time you open that app again for the rest of the day. But the next day it starts all over again.
More information answers:
1. All logins are performed locally using user or domain admin accounts as appropriate. Issue manifests on all logins.
2. Every user sees this on their workstations, admins see this on any workstation or server that has Office 2010 installed.
3. We are using a domain system which is not allowed unrestricted access to the Internet. There is a heavily filtered web proxy in place, and routing is working to get user traffic to the proxy portal as needed. Because of the sensitive nature
of the environment we're in, we don't want Office apps to try and contact any download sites for any reason. Since the user isn't manually initiating the connection, the calls to that URL should not be happening in the first place.
Steps to narrow it down further:
1. Performing a 'clean boot' per your link prevents any domain credentials from being used, so only local machine admin can log on, and the local admin cannot attempt to connect to the web proxy at all, so the nag boxes don't appear when using Office apps.
2. Office Safe mode on a normally-booted system makes no difference, same nag boxes appear.
3. Users do not have access to Internet Options, so cannot save proxy credentials. Admins can see the settings but cannot change them, as they're locked down by Group Policy. We don't want the outgoing Office web traffic to be allowed in the
first place, so this is a wasted step.
Final items: Trusted Sites manipulation, etc. Not going to happen. We can access the Internet whenever we want, comms to the Web is NOT the problem. We want to prevent Office from trying to contact the Web
on it's own.