Currently I use my notebook without an external display, and the following happens:
a few weeks ago it started to lose signal occasionally.
And it’s a really short period, because after my screen goes black, it instantly “starts to come back”.
I tried using this display via HDMI: https://www.acer.com/ac/en/GB/content/model/UM.HV0EE.P01
And it seems that it’s much more regular on the 2K display, than on my 1080p integrated screen.
Here is what I’ve experienced with an external display:
Another has just happened, and it was simultanous with the refrigerator’s fans turning off. Later, it happened again when the fridgerator turned its fans on. I will watch out whether there are more “suspicous” things or not.
Now for 3 minutes, it happened like every 45 seconds. And I didn’t notice any electric change in the room.
I pulled out the charger from the notebook, to see if there is any difference, and after a few minutes, it began to turn off like every 4 seconds, sometimes they even overlapped, causing long black screens.
It also seemed like when I moved the mouse, it got black. I pulled out the mouse, and the frequent black screen suddenly stopped.
Then I put it back after half a minute, and it’s still not that frequent, but there are black screens again.
The problems seem to be power-oriented:
The fact that turning electrical appliances on/off in the house causes
problems may mean that the electricity in your house is not well isolated
and some appliances cause strong electrical surges, which is quite dangerous.
In that case the computer needs to be protected with a UPS
or at least with a surge protector.
The fact that the computer cannot work without the charger may mean that the
battery is nearly dead.
As this happens very rarely outside of your house, but still happens,
and that connecting devices also has a negative effect,
might mean that your Power Supply Unit (PSU) is weakening.
If the computer is new, use the warranty to have it replaced.
A repair-shop will have the tools and replacement parts to better analyze the
problem. However, if the computer is quite old, ask for estimates for the
repairs to see if the investment is worthwhile.