Metro Apps won't open (including Windows Store)

I am running Windows 8 Enterprise, on a domain account linked to a Windows Live ID. No Metro Apps will launch (Mail, SkyDrive or Windows Store).

When trying to launch Windows Store, the errors in the event log are (please pardon my french) :

• Application: (5973) Échec de l’activation de l’application winstore_cw5n1h2txyewy!Windows.Store avec l’erreur : Unknown HResult Error code: 0xc0020017 Pour plus d’informations, voir le journal Microsoft-Windows-TWinUI/Opérationnel.

• System: (7000) : Le service Service Windows Store (WSService) n’a pas pu démarrer en raison de l’erreur : Le compte spécifié pour ce service est différent du compte spécifié pour d’autres services s’exécutant dans le même processus. which should translate to The account specified for this service is different from the account specified for other services running in the same process.

My system is up to date with the latest updates. Note that if I double click on an image, I get a popup saying (translated) File system error (-1073610729).

I have tried running sfc /scannow without effect (the logs are enormous though, with a lot of missing files, or duplicate ownerships). wsreset.exe fails with the same error as above (File system error (-1073610729)). chkdsk /r /f solved nothing either.

A local account has the same problems on my machine.

I think everything worked when I installed the OS (from scratch), but this has been happening for a long time now, and I have no idea of what triggered this behaviour.

There are many posts related to Metro apps not installing or working when connected to a domain, I will post my solution here.

I found that metro apps are dependent on access to MANY registry and file locations.

I determined this by using Process Monitor by SYSInternals.

After playing around with registry and file permissions certain apps started working, including STORE, MAIL, CALENDAR, PEOPLE.

The permissions required are identified in this Microsoft document.

Warning: do not overwrite permissions of child objects in the registry - there are many child objects with custom permissions and it can make your problems worse

But other apps would STILL not open or would hang indefinitely including FINANCE, WEATHER, FOOD, TRAVEL, SPORTS.

Finally managed to fix it by giving "ALL APPLICATION PACKAGES" full control to the registry key:

HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppModel\SystemAppData