Catastrophe Averted!
I found out what was causing the problem mentioned in my last post and it wasn't the extension. Just a quick, brief recap:
I had to do some code conversion from Visual Basic to C#. The reason is irrelevant to the story.
There was lots to do, so I installed an extension and it worked like a charm. Everything converted perfectly and, aside from some minor manual changes I had to do, overall it was a great success.
I closed down Visual Studio and opened File Explorer to do some other stuff; that's when I noticed the problem. I clicked on a the wrong folder and when I clicked on the correct one, both were selected. It was as if Ctrl was being held down. I couldn't open folders, instead the Properties window would open instead and any keyboard use was impossible as nothing would appear on screen in text boxes or search bars etc.
I reset Windows, keeping my docs and files but removing all software (as I suspected it was the extension somehow; I know it's a big leap however, I've experienced odd behaviours with other extensions so I feared it was some major bug).
When my system was eventually up and running (after the reset), the problem was still there. In a last ditch attempt at something, I forced a shutdown (because I couldn't select it using the mouse), aggressively rubbed the keys on my keyboard and blew into all the ports along the edge of my laptop. Yes, crazy I know.
I started up, and everything was fine again.
I spent two days reinstalling all the software I use for work and a couple of personal apps. I had to do another code conversion so, having suspected that it was actually a keyboard issue, I installed the extension again and did a conversion (I work from home but today I was at a colleague's office who also works from home). Everything was fine.
I got home later in the day and I opened up my laptop to do some more work (I love my job), and suddenly the problem was there again. I was on the brink of a full-blown panic attack. I didn't know why this was happening and the keyboard trick didn't make the slightest difference.
While I experimenting (and contemplating the depths of despair), I noticed the error only occurred when my wireless mouse was connected. If I disconnected it and then hit the Windows key, everything worked as expected.
My partner then made the brilliant observation: where's the wireless keyboard? I'd been using my laptops keyboard with a separate wireless mouse (which shares a single dongle with the keyboard), and the problem was clearly linked to the dongle from the wireless mouse/keyboard.
The problem all along? My wireless keyboard was under my desk, and something was on top pressing several keys.
I felt a wave of relief and then a wave of shame at the stupidity of it all. Such a simple thing yet I'd jumped to more complex conclusions.
I learnt a lot today. Most importantly, I learnt to be more patient and thorough (a regular item on my self-development list).
As we know as developers, it's often a simple error which prevents a build or causes an error; sometimes as simple as a character missing or in the incorrect place.
We can all benefit from being more patient, thoughtful and open-minded.
Touch some grass and take a breath of fresh air, it can work miracles for the mind.