Been like this for many versions. I simply can't click things at times, I have to repeatedly press v, and then it doesn't work after 10 clicks at times.

You're going to have to be more specific

I repeatedly try to click a joint sometimes, and it doesn't work for shit, it even highlights but clicking scrolling pressing z or x has null effect. Pressing the v key seems to be like intermittent response. Sometimes when I alt tab I can't click anything at all, sometimes only the neck.

Try to
1. Don't full screen and don't press the right click
2esc-setting/options/mouse(change it to 1)

Did you, by chance, change the aspect ratio of the game's window?

I don't ever right click, fullscreen is off but at native res, mouse buttons are on 1 too. No haven't changed the aspect ratio either.

I am sure many have noticed this over the years?

One thing that might help is if you press the esc button and then try to click something. Perhaps you're on an invisible window or the like.

It could just be a problem with your mouse. Have you tried using a different one?

It also might just be lag.