Built in keyboard malfunctioning
On Win10 keyboard produces only uppercase when CapLocks is OFF and Shift is not pressed. Other times it only produces lowercase when CapsLocks is OFF and Shift is pressed. Sometimes after keeping both keys pressed while typing some words it reverts to normal functioning, sometimes not.
Anyway character case doesn´t change spontaneously while typing. Anomalous states are stable until Shift or CapsLock are manipulated or power is turned off. At start up the state may be anomalous or normal randomly and independently of last state. Machine is HP Intel i5-7200U LapTop