I am having a similar issue, however, all I am trying to do is sign into an existing Microsoft Account, not create a new one.
My predicament occurs for various reasons: First and foremost, whenever I try to sign into the Microsoft Store, the sign in pop-up windows flashes on-screen for less than a second before disappearing. Repeated attempts ensue the same outcome. Similarly, attempting to sign in to anything Xbox-related (in my case, Xbox Live via the Minecraft Windows 10 Beta app), the same issue occurs -- the sign in window pops up for less than a second before disappearing. Additionally, whenever I investigated the problem by navigating in to Settings -> Accounts -> "Your email and accounts" (on Windows 10) and trying to manage any of the accounts under "Email, calendar, and contacts" or "Accounts used by other apps" the same issue occurs (of course, clicking "Manage my Microsoft account" opens in a browser).
I've had this problem before and I believe I've fixed it without having to create another account, so if that is possible, that would be best. If not, as long as it is possible to delete any created users as I only need the one, the one that seems to be having trouble again.
If you need any other information, feel free to request it, I'm sure I could find it for you. Please, help.