Login with Google - Device link failed and blank popup screen

I recently put Avast on my Android phone and then decided to change my Laptop to Avast as well. I paid for the ad free version on the phone.

After installing the product on my Windows 7 laptop, I clicked on sign in, Sign in with Google, but I get a blank pop up screen where you would expect the Google login to appear. Closing and clicking Sign In again results in Avast stopping and displaying an error message, I then need to restart Avast completely.

My mobile is all set up, logged in with Google & operating. On myavast website I can see my phone and it also displays my laptop but says it has no info. All other antivirus products have been uninstalled, Laptop rebooted, e.t.c. but I still get the blank popup screen. Oh and if I try to login with my google email & password it says account doesn’t exist.

Any ideas?

Repair Avast:
Control Panel> Program and Features (Add/remove program)>Select Avast> Select Repair. Reboot when completed
https://www.avast.com/faq.php?article=AVKB204

If Repair doesn’t fix the problem, try the following:
Clean Install of Avast:
https://goo.gl/4Ptzkf
If you need additional help with the Clean Install, watch this:
https://youtu.be/p-h3myRD51A