Flickering scrollbar

I have a problem that in story view, sometimes the horizontal scrollbar for the story pane flashes up and then immediately disappears. It then keeps doing that regularly, about once a second. It appears to relate to the particular page I’m looking at - if I go to another page in the same feed, it loads fine, and then come back to the first one I get the flickering again. It’s VERY distractring to reading!

I’ve seen this for a good long while now. Today it came up on the feed for The Register (http://www.theregister.co.uk/headlines.atom) specifically on this story:

It’s unaffected by size of browser window or panes or anything.
I’m running Google Chrome ‘Version 45.0.2454.101 m’ (latest at this moment).