Laptop screen randomly switches to external monitor

[AJQS]

Well looks like the decision to buy this Toshiba was a wrong one. It's started randomly switching the display output to external monitor, even though I don't have one plugged in!

I had read about them shutting down randomly due to capacitor failure but I was convinced mine was still running just the screen had gone off - so today I plugged an old monitor in and yes it was still running! Pressing the hotkey to switch screens brought it back to laptop screen.

What actually causes this though? I've been googling it with no success. Is it worth fixing?

 

[RobertP]

My wifes old laptop (samsung) used to go to a black screen sometimes. The inverter for the backlight was playing up but would work again after a reset. That just meant closing the lid and lifting it again to make it work.

I opened it up and secured the leads to the inverter and it then lasted longer but still did it sometimes. When the screen backlight failed, if you shone a bright light on it from say a torch you could tell there was something there so if yours is a backlight problem you may be able to confirm it.