Browser very slow to load

After starting my XP computer, using Avast Free Antivirus, when I try to start a browser like Firefox or Chrome, it takes FOREVER for the browser to load – a least a minute or two. During this time, the Avast logo is alternately spinning and still in the tray. Once the browser finally starts, it won’t go to a URL or let me search for another minute or two. What is it doing all this time? And why is it preventing the browser from starting? Thanks.

Have you just installed avast?

No I’ve been using it for several months.

P.S. It’s nearly impossible to read the Verification images.

Perform a clean installation of the latest version:
https://forum.avast.com/index.php?topic=169255.msg1203279#msg1203279