Windows keyboard won't type capitalized T

I'm trying to simply type capitalized T on my 64b Windows 7. What happens is this. Everything works fine. Keyboard types letters, small or capitalized until I get to letter T. Only here it doesn't work.

I have Windows 7 Ultimate and keyboard is connected via USB.

This isn't program related, but rather system wide bug.

Has anyone had some problem like this.

This sounds like a hardware failure. The keyboard is connected internally in a matrix layout. This means that connections are shared between multiple keys to reduce the total number of connections needed to the control chip. Normally this is not a problem, but on some keyboards, the keyboard can't register all the keys if you press 3 or more keys. This is because some combinations could be caused by multiple different key combinations, and the keyboard can't be sure of which combination you pressed.

See for example the keyboard matrix pad below, which would sit under the keys. The three parts are sandwiched together. There are two plastic sheets with conductive traces, and an isolating plate with holes in between. When a button presses down from above, two points on the plastic sheets make contact through the holes in the isolating plate.

If you would for example Q and S, and then press A or W, the keyboard controller can't be sure which of them you pressed, because the same electrical lines are all short circuited.

The exact matrix layout is different between keyboard models, and I would guess that there's some hardware fault that makes two points short out when you press T or P, triggering the same kind of error condition where the keyboard controller can't be sure what is being pressed. This could have various causes like liquid stuck between the contact pads, or a misalignment. I would suggest getting a new keyboard, and if you're curious, taking apart this keyboard to see how it looks inside.

In my case the uppercase-a would not appear when typing it. After an hour of unsuccessful problem-searching (plugging the keyboard into different USB-ports, uninstalling and reinstalling the keyboard drivers, going into the PC's UEFI to check the legacy USB setting, case-reading on the internet) I suddenly realized the cause: Some hours before, I had installed a screen capture program and in there I had stupidly assigned Shift-A to be the video capture hotkey. So that was taking priority of that key combination. I could have realized earlier that the problem was related to the screen capture program because when testing if an uppercase-a could be typed into the password box of the Windows login screen, this went without a problem. But once in Win 10, no uppercase-a possible. Well, the reason for that was that during installation of the screen capture program I had configured it to start when Windows starts. Long story short: See if there's a program on the PC taking priority of the troubled key(s).