First, thank you guys for your help. Special thanks to Sean for recommending KeyboardStateView.
Yesterday It happened twice, but it takes awhile before it happens and by then, I'm immersed in my work and I just couldn't pinpoint what exactly the cause was. Even when trying to pay close attention, I just couldn't replicate it.
Today I couldn't get it to work, so I took a break and when I came back, ctrl+z wouldn't work?!.
I have an outside program that pops up every 10 mins. I have hidden it at the very bottom of my screen, and is why I probably never noticed it before.
KeyboardStateView Shows the popup triggering Alt key 18, and Right Menu key 165, and not every time but most of the time renders ctrl+Z inoperable.
I pressed Alt on the right side and the Right Menu Key and
voila, I have ctrl+z again.
Oddly enough, I'm currently working on a popup in in Affinity🙂.
Thanks again for your quick responses and help.