Can't add account or download from store- started with a live login

Hi, I upgraded from Win 8.1 with a live id some weeks ago. In 8.1 I never used the store.
1. Any download I attempt from store => "Try again. Problem at our end'
2. I read that creating a new user account might be appropriate. But I can't do that. At one point I was asked to Verify my account.. but that failed. So I was prompted to change to a local account.
3. I can log in with my login details to MS Live.com
4. 'Add someone else to this PC' does nothing when clicked.
5. I am logged in as admin.

6. At "Your account" , logged in now as a local user, nothing happens if I click 'Sign in with a Microsoft account instead'
How can I set up a new user with a live login?

Thanks!

So, using msconfig and task manager, I've worked out it's some startup program that affects both the Store download check and the user account management. Having disabled most of my startup programs the system dialogues appear to work now. I guess it will just take time and patience to find out which of the small programs I've used for years interferes with these particular Settings and Store download dialogues.

PowerMenu proved to be the culprit- certainly as regards the User menus. It adds 'On top', 'transparency', 'minimise to tray' etc to the title bar rt click menu. A tiny old utility.

Want a replacement? This seems to work: Moo0 WindowMenuPlus.
Add Options in Windows Title Bar Right-Click Menu

Using the title bar right click menu avoids issues with adding buttons, for example. On the other hand, you don't get a visible indication a window is on top. (And- e.g. - Filebox Extender's button doesn't immediately update).