Hi,
When I try to sign in to my microsoft account via the store, cortana or settings, a grey box appears then after a couple of seconds will disappear. This means I cannot sign into my account at all! i had tried searching solutions on google but there's only a website that had the same problem, but it didn't seems to had a solution.
http://www.tenforums.com/user-accounts-family-safety/17034-grey-box-appears-then-disappears-when-signing-into-microsoft-account.html
(website that contain user asking same problem)
Any help much appreciated, I am running windows 10, on a Dell laptop that used to run windows 7, also it is a 64 Bit. If you need any other information, please ask
This image below is copied from another user that had the same problem.