why does my laptop keep flashing

Joanm123

Commendable
Apr 8, 2016
1
0
1,510
This laptop is so annoying!! whatever I am in, or doing on it, every 30 - 40 seconds, there is a flashing on the screen - its like a subliminal message that I cannot see, or read, it just flashes up a box and then is gone in a second! Very, very annoying - Help??????