No joy with any of this. I have cleared the cache in Opera, Chrome and Firefox and I get the same result - the login screen stays on the screen. However, the previously-used browser then gives me a log-out message saying that I have logged in from another device. So, it appears to be logging me in but freezing on the login page after clicking the Log In button. Strangely, it now seems to work on my Android phone where it wasn't yesterday but I need to log in from a browser to download videos to my PC.