Specific keyboard key's combination won't work (such as Ctrl+Shift+Z)

Hello,

I use Photoshop and Illustrator a lot, and the default Redo shortcut is Ctrl + Shift + Z.
I have a brand new PC, and it worked fine at the beginning - as far as I remember, but all of a sudden it stopped working. I don't remember if it happened after some Windows Update or after I changed my SSD, which was defective.

I contacted Adobe support but it turns out it wasn't their program's fault.

Testing my keyboard on an online keyboard tester http://en.key-test.ru/, I learned that all keys work fine on their own and most combinations too: if I type Ctrl+Z, it works; Shift+Z, it also works; and so on, but SHIFT+CTRL+Z won't work, as well as SHIFT+CAPSLOCK+Z and SHIFT+CAPSLOCK+X.

It doesn't make sense. Shift+Alt+Z works fine. Ctrl+Alt+Z also works. Ctrl+Shift+X has no problems. So why wouldn't Ctrl+Shift+Z work? I looked for an answer online and couldn't find one, and I thought I should ask if this has anything to do with any Windows configuration before I buy a new keyboard.

Oh, and by the way, I just formatted my SSD and installed Windows again, just to be sure.


Thanks in advance

- Pedro