Bill, I did install a freeware ad blocker, but now I can't find it, mostly because I can't remember what it's called! Not in Programs, not in Downloads, not in ADD-and-Remove. It IS working, but in a half-arsed fashion.
As I said above, it removes the script from the box, but the box is still there, and so I get the 'jumps' as they develop in the thread page. Five boxes on this thread, each as big as a three-line post.

So, I open a thread, click on what's new since I was last there, and before I can read the post, I'm a post or two further up. So, I find my place again, start to read....
Never used to happen.

I only downloaded Avast because AVG threatened to start charging me quite dearly for their VK. Then they didn't. Both VKs seem to be working reasonably well in parallel.
I just wanted to know if anyone else suspected Avast.