Threat Secured Pop-up

For the past week I have been getting a AVG 'Threat Secured Pop-up' every 5 minutes while online. 

I have taken a screenshot but when I clock on the Image (mountain) button I don't see anywhere I can attached it to this post. 

The threat secured message says the following; 
"We've safely aborted connection on clients4.google.com because it was infected with HTML:RedirME-inf [Trj]" 

Threat Name: HTML:RedirME-inf [Trj]
URL: https://clients4.google.com/chrome-sync/command/?client=Google+Chrome&client_id=BDPvXeEMzgQ0Z1aRXiqFBA%3D%3D
Process: C:\Program Files\Google\Chrome\Application\chrome.exe
Detected by: Web Shield
Status: Connection Aborted  

I use Chrome as a browser and Google.co.uk as my homepage. I have never been on the site clients4.google.com and had never heard of it prior to these pop-ups appearing. 

I have updated AVG thinking that may have been a problem but no change.
I'm using AVG Software Version: 18.2.3046
Virus Detection Version: 180528-0
I'm a free user (not paid) 

I have been into my Control Panel and nothing new has been installed recently, no add-ons either. I read on another AVG topic to try right-clicking on desktop short-cuts and checking the properties. When I do that for Chrome and others they appear normal. Chrome for example showing as "C:\Program Files\Google\Chrome\Application\chrome.exe"

Advice and support on how to prevent and remove this pop-up / virus would be good.