Solved. Faulty USB hub, with mouse attached.
Hardware can do some weird things.

Ok - computer has reverted to faulty settings as above, after sitting idle overnight. Any ideas?

cmd - sfc /scannow nothing found.
Ran the two cmds as prompted:
regsvr32 "%SystemRoot%\System32\actxprxy.dll"
regsvr32 "%ProgramFiles%\Internet Explorer\ieproxy.dll"

Have rebooted and...

Have found similar problem from Win7.
"Open each folder in the same window" not working

Will try the fix ----> cmd - sfc/scannow and see what happens...

OK - have confirmed that the problem seems to be that I can no longer 'Open in Same Window'.
This appears to be the same behaviour that is affecting the Browser links as well.

Still, doesn't seem...

OK - have confirmed that the problem seems to be that I can no longer 'Open in Same Window'.
This appears to be the same behaviour that is affecting the Browser links as well.

Still, doesn't seem...

OK - have confirmed that the problem seems to be that I can no longer 'Open in Same Window'.
This appears to be the same behaviour that is affecting the Browser links as well.

Still, doesn't seem...

OK - have confirmed that the problem seems to be that I can no longer 'Open in Same Window'.
This appears to be the same behaviour that is affecting the Browser links as well.

Yes - that is my preferred option. I have Windows set to open in the same window. This does not work.

If I click on Explorer and open a Folder, it opens.
If I click on the next level Folder or...

Hi Kari

I use Single Click to open files / folders (changed from Folder Options as you describe).
I guess another way to describe the problem would be - files/folders/browsers are unable to open...

Hi
I am unable to open files/folders/browser page with Left click.
Started about a week ago. Win10 appears normal with no new updates.

All programs open, but files/folders will not open in same...