[MikeBmusic]

Final follow-up with the old computer (probably)

Ran the updates, still had the same crackling noises. LatencyMon showed that the computer should be ok for audio.

Then I tried to boot up the old Roxio s/w I have been using for video editing. Would not boot up at all. (It ran fine before all the Win updates).
ARRGGHH - I did a system restore, computer would not do a restart after. Cold re-booted a couple of times, it finally started up (I actually left it for a few hours and when I came back it was on).
Tried Roxio - nope. Reaper, still crackling.
I was trying to edit a quick video I had shot, and found that whenever I tried to move the raw video file from the SD disc, Windows Explorer would crash! Eventually, I copied it onto my other computer, put it on a USB stick, then accessed that on the recording computer (different video s/w) directly from the USB stick.
Decided it was a very good time to backup my recording/music files (x3). One of my USB drives had a video file on it from when I had used it to transfer the file to the other computer, and Windows Explorer crashed when I tried to delete that file, too.
So after all that, I tried Reaper again, and it was coming up with an error - could not access the Focusrite. I downloaded and installed the drivers again, nothing! Tried different USB ports, tried rebooting computer, plugging/unplugging interface, nothing made a difference.
One interesting thing - when I had the computer on (rebooting0, interface turned off, but monitors on (plugged into the interface), there was a fair bit of low crackling/buzzing matching the sound of the hard drive booting up. When I turned on the interface, that noise went away.

I moved the Focusrite to the Win 10 computer, downloaded the drivers, and it worked fine - no crackling (using headphones to check (crackling on the other computer was with both monitors and headphones).
New computer is on its way.