Sign-in issue

Hi there,
Issues with my 64-bit Windows 8.1 Sony Vaio laptop:
Due to PC issues today I uninstalled Avast, downloaded the latest version, and then installed that.

That all appeared to run correctly, and certainly Avast now indicates “You Are Protected”, “All shields active” and “Everything up to date”.

However, if I try to sign-in then I get the message “Your device has been disconnected from your Avast account, please sign in again” and a blue “Log Out” button is beneath that message.
If I press this “Log Out” button then absolutely nothing happens.

If I go to my account on Avast web site then the system indicates I’m “Unprotected”.

Obviously out of step in some way, but how do I correct this situation?

Connect the system to your avast account.
https://my.avast.com/#home
“secure another (or new) device”