Keyboard bizarre

I have an erratic keyboard.

Every so often (?every few weeks) on booting up the Caps Lock light shows

that the Caps Lock is on and the computer will accept a password to boot up

but after boot up the Caps Lock will go into reverse (the light will come on

to indicate that the Caps Lock is off). This is only a slight

inconvenience, more of a curiosity. Does anyone know why it may act in this

bizarre way?

Thanks.

Bill Ridgeway