Question On and off random keyboard typing - cant get passed log in

Apr 19, 2019
Wondering if anybody has any advice: few weeks ago I was streaming a sports game (paid for, legit stream) and suddenly my laptop screen goes black and kicks out to the log in screen, weird, tried to type in my password to get back in, but I had no control over the keyboard to get anything in the password field was just filling up with loads of the black dots, as if I was typing but I couldn't even manage to type as it was constantly adding more and more black dots. I managed to press the button to "show text" and it was just filling in lots and lots of "e"'s . I managed to restart the laptop and got to log in screen, all fine, password typed and stream back up and running.

Fast forward few weeks have been using the laptop inbetween with no issues whatsoever, today switched laptop on and log in screen appears, I click to start typing password and then once again loads of black dots auto filling in the password field out of my control I am trying everything in my power to backspace them but they are just constantly filling up! I manage to click the show password again and this time it's typing "f"'s. Shut laptop down, back on, and I am now logged-in fine! But i am typing this from an external keyboard plugged it in to USB and it has started working fine, just to see if it happens again, but I have not disabled the laptops keyboard, Should I? What is causing this? The laptop/keyboard is clean nothing seems to be stuck under the keys or anything. Is it a virus? Confused as to why it is only happening at random times as the laptop has been fine for weeks since it first happened but now it has happened again? If it's a dodgy key (or keys as e&f are close together) how can it be selective in choosing to type randomly? Should I disable the laptops keyboard?

The laptop is a Toshiba Satellite C850 1KN running windows 8. Admittedly a bit old think I bought it in 2013 but I only use it for general browsing and streaming, itunes, storing some photos etc I don't play games and I don't really download much, the memory is nowhere near full laptop states "480GB is free of 687GB"