I've just upgraded to Windows 10 and now on the home screen it constantly flashes/refreshes. How can I fix it?

[Windows Central Question]

I've just upgraded to windows 10 and now on the home screen it constantly flashes/refreshes

i can't access anything on my computer, i can see the icons and the windows start menu icon but cannot click to open any of them. the cursor is constantly "whirling" around as if it is trying to locate something.
any help will be greatly appreciated