Three times in the last hour the monitor went black. Most times just everything dissappears at once and it is black.
The little light beside the on/off switch, however, is still on orange - which means that there is still power.
The last time it was a bit different. For a few seconds there were systematically arranged rectangels on the screen. Columns of about 5 cm breadth each, the first column coloured, the second not (you could still see the normal content of the screen), the third coloured again, the fourth like the second and so on. Within the columns there were rectangles like in a table, each about1-2 cm high. Again one was coloured, the next you not, then coloured again, then not, and so on. It looked quite fantastic and well organized! After a few seconds it dissappeared. I have seen these rectangles several times before, but as I said, usually the screen just goes blank at once.
I have replaced the Monitor with a new one. Whate else could it be and how do I test for it?