Can't access Microsoft websites after logging in with my Live ID

The problem

When being logged out, I can see the Microsoft web pages. I have trouble accessing Microsoft websites after signing in with my Windows Live ID. For many pages I try to access, it redirects me to an error page. However, I need to login in order to access some resources, e.g. the Windows 10 Insider builds (related SuperUser question).

My login

AFAIK, I have only one Microsoft Live account and I maintain my password with KeePass since years, so it's unlikely a credentials issue. There's no error message about invalid username or password. I have received emails from Microsoft on that account lately (June or so). In addition, I was able to update my Visual Studio Community edition license using that account today. All in all I'm quite sure it's the correct email address and password that I use to log in.

Environment

My default OS is Windows 7 x64 SP1 Professional and my browser is Firefox 48.0.2 with Adblock Plus and HTTPS Everywhere installed. I don't need a Proxy and I have not enabled proxy settings. My virus scanner is ESET NOD32 9.0.402.0.

While the Windows language is English, my keyboard is German (default) but I can switch to English and Chinese. I notice that Google searches often bring me to German Microsoft pages, e.g. the German version of MSDN. I'm not sure if this relates to the issue.

I have tried others (see below).

I am connected to the Internet via Ethernet (private 192.x network) that goes over an unmanaged switch directly into a DSL router (Fritz!Box 7362SL). My line is 50 MBit/s downstream and 10 MBit/s upstream. A speed check roughly confirms that. There's nothing noticeable about the Internet connection in general. E.g. I can access my server via SSH, StackOverflow works well etc.

C:\Users\Thomas>nslookup microsoft.com
Server:  fritz.box
Address:  fd00::ca0e:14ff:fed7:9909

Non-authoritative answer:
Name:    microsoft.com
Addresses:  23.100.122.175
          23.96.52.53
          104.43.195.251
          191.239.213.197
          104.40.211.35

Issue details

When I enter microsoft.com into my browser's address bar, it redirects me to

https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/de-de/

On that error page, I can click various links that also generate an error:

"Download Center" (http://www.microsoft.com/en-us/download/default.aspx) 
--> https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/en-us/download/
"All Microsoft Sites" (http://www.microsoft.com/en/us/sitemap.aspx)
--> https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/en-us/sitemap.aspx
"Microsoft Worldwide" (http://www.microsoft.com/en-us/WorldWide.aspx)
--> https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/en-us/worldwide.aspx

Most important to me at the moment is the Windows 10 ISO download link that does not work as well

https://www.microsoft.com/en-us/software-download/windowsinsiderpreviewadvanced
--> https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/en-us/software-download/windowsinsiderpreviewadvanced

Some other pages work:

"PC Hardware" (https://www.microsoft.com/accessories/en-us)
"Security Essentials" (http://windows.microsoft.com/en-US/windows/products/security-essentials)

Question

How to fix it? Of secondary interest: the technical details on how this can happen and learn about other possibilities of troubleshooting such an issue.

I have tried

The question I can't access any Microsoft website did not reveal things that I considered as interesting.

On the same system:

• logging out and signing in again
• typing the email and password manually instead of having KeePass type it
• disabling Adblock Plus in Firefox
• disabling HTTPS Everywhere in Firefox
• disabling ESET NOD32 for a while ("pause protection")
• using Google Chrome 52.0.2743.116 m
• using Google Chrome 53.0.2785.89 m
• using Internet Explorer 11.0.9600.18426 (Update version 11.0.34)
• using Opera 39.0.2256.48
• disabling IPv6 support of the Ethernet LAN adapter
• switching the User Agent to iPhone 3.0
• looking at C:\Windows\System32\drivers\etc\hosts - it does not contain any entries
• checking the proxy settings - it's "no proxy"
• uninstalling ESET NOD32 and rebooting the system

In a VMWare 12.1.1 build 3770994 VM with Windows 7 x64 SP1 Home Premium:

• no Adblock Plus installed
• no HTTPS Everywhere installed
• no virus scanner installed
• Internet Explorer 10.0.9200.17609

In a VMWare with a modern.ie VM Windows 8.1 Enterprise:

• Internet Explorer 11.0.9600.17416 (Update version 11.0.14)

In the Firefox network analysis I see the following when I enter "microsoft.com" in the address bar:

• using HTTP 1.1 Request URL: http://microsoft.com/ gives a HTTP 301 "moved permanently"
• using HTTP 2.0 Request URL: https://www.microsoft.com/ gives a HTTP 302 "found" with Location https://www.microsoft.com/de-de/
• using HTTP 2.0 Request URL: https://www.microsoft.com/de-de/ gives another HTTP 302 "found" with Location https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/de-de/
• using HTTP 2.0 Request URL: https://www.microsoft.com/library/errorpages/smarterror.aspx?aspxerrorpath=/de-de/ gives HTTP 404 "not found"
• [...] downloading of resources describing the HTTP 404 HTML page

Using Wireshark I can see it's sending a cookie. The content is cryptic, probably like it should be because it only stores a few hashes. I can also see that it connects to an IP address that was not listed by nslookup: 104.124.113.193. IMHO that's ok, because it uses some Akamai load balancing or similar.

I went to the URLs http://live.com to check what information is saved in my profile, but everything seemed ok. From there I followed a link to a linked profile that brought me to my Skype at https://secure.skype.com/portal/profile. The Skype site required me to enter my first name and my last name before I could proceed. Since that time, I am able to go to the Microsoft web sites.

My impression is that my account setup was incomplete which caused an error on Microsoft side. I doubt it's intended behavior, because I would expect Microsoft to prompt for the missing information instead (like it was done on the Skype page).

Perhaps it's relevant to know that while I created a Windows Live account in 2010, I never actually used any of the online features. I can only recall that I signed in to activate a copy of Office 2013 once and I registered for the Windows Insider program. I use the same account for Skype and Visual Studio, but that does not require me to go to a website. Therefore I have never completed the required information before.