Control key acts as if it is stuck periodically

Generic fix for this generic issue: press stuck key or Ctrl+Alt+Del, Esc.

Symptoms: This issue is not limited to Ctrl, but can occur with any other modifier key (Shift, Alt, Win).

Recovery: Most of the time, Ctrl+Alt+Del re-sets key status to normal if this is happening. (Then press Esc to exit system screen.)
Another method: You can also press stuck key: so if you clearly see that it is Ctrl which got stuck, press and release both left and right Ctrl. This allows system to see key press and release events (again) and thus detect correct status of these keys.

Cause: This occurs when the operating system did not notice releasing a key. But what can make the operating system not noticing a key release? I guess the answer to this can be very tricky and almost undiscoverable, because it might easily originate in subsystem seemingly non-related to keyboard. For example, badly written driver for some hardware creates a delay during which Windows skips the detection of released key. This is difficult to answer and could be very difficult to debug.

Scope: I have also seen this on many various computers, regadless of model or make. From my observation, this was not common up to Windows 7, but became more common in Windows 8 and 10. If the above recovery works, do not suspect your hardware, it is typically a software issue.

Note: If you have connected multiple keyboards, Ctrl+Alt+Del has to be pressed on the keyboard which has the key stuck. Pressing it on the other keyboard does not reset state of the stuck key.

I found the solution because I got this issue with different laptop and for each one the fix is different. I have found the cause because of software conflict that is some software trying to use your keyboard at the same time making the ctrl key stuck.

For temporary fix you can try each of the following to see which one will work for your laptop:

1. Press both ctrl at the same time
2. Press both ctrl + alt at the same time (Dell 1545 worked)
3. Press both ctrl + shift + alt at the same time
4. Press both ctrl + shift + alt at the same time including the Fn key (Lenovo)

If it still does not work, opening the on-screen keyboard from control panel can temporarily unlock the ctrl key

However for a permanent fix, I downloaded SharpKeys and disable the Right Control, this has solved the problem. So you should find which of the two ctrl keys is causing the problem and disable one of them using this software. It should work. Else you may have to disable both and use on screen keyboard if you need the control key.

Just pressing the Fn key helped get me out of the issue. It's an odd thing to get stuck in and frustrating to get out of. I tried the other things like pressing right click and left click, all that. None of that worked except for the Fn key.

Works on Dell Inspiron 15 3000 Windows 8.1.

Hope this helps!