oh johnny boy ... the lights ... The lights are fa-a-ling ...
we could do with a little better description of just what's going on.
Is it like a cartoon .... you switch on .... the monitor switches off .... as you extend a finger towards the case ... the monitor glows faintly. You stab the off switch .... storm out of the room, slamming the door behind you .... as you turn ... you can see the faint glow of a screen coming from under the door ........
or is it more boring ... have you checked Control Panel | power properties | schemes
it the screen off time set for 2 seconds or less?
could the processor be overheating and the machine is shutting itself down?
could the video card be overheating and the machine (or just the display) is shutting itself down?
have a look inside ... does it look like an exploded teddy bear in there?
is it a CRT or LCD? if CRT ... could the set be overheating?
does the screen "fizzle" as the screen goes off?
(if CRT don't look inside there are lots of volts running round in there ... and they bite!!).
Heathcliffe .... (are you that the surly alcoholic love child of Mr Earnshaw (the well known dictionary salesman)?