Resolved KB4074598 messed up my system

When I click a YouTube link the computer freezes with no mouse response. After a while, it unfreezes and I get an error message telling me to try again later.

Even when I go to Facebook and there is an embedded YouTube link that I scroll past, the computer freezes temporarily with no mouse response.

It's the same on both Firefox and Internet Explorer.

It's any video, not only YouTube, that doesn't play.

Anyone else?

(To check, I have been running my LapTop with Windows 10 and Firefox in parallel, clicking the same link with no problems at all.)

 

I did what I usually recommend in cases like this. I sat on my hands and today, the Windows 7 system is back to normal. Strange though ... ... that two computers on the same connection behave in different ways and the next day ... ... they both behave the same way, the way they should.

No issue with KB4074598! Well ... ... not today at least!