Computor help needed.

Over the last few weeks, my laptop, has closed the window I am looking at.
The screen changes to a purple colour and the writing, in white, states, “He’s dead Jim”, underneath that, is other writing, but it goes off screen in a flash, and it’s gone before I can read it.
Anyone any ideas as to what causes this?.
I have Virus scanned etc, but all seems O.K.
Anyone any ideas?.
Jim.
Lincoln .7