computer clicks on and off by it's self

still haveing problem with computer "clicking off by it's self,when computer clicks off there is like 11 to 13 diffrent computer programing stuff can't get to read all of the computer stuff because i can only see it for like 30 secondes,then computer screan has lines that go up and down there is like over a dozen or so lines that just are up and down half the leangh of screan then computer blinks on and off from computer programing stuff then to white lines,also there are stars in the color of orange-next to that it syas speech-dispatcher configure for user session,,,also it says pulseaudio configure per-user session all of this is on the left hand side of computer screan then on right side of computer screan it says starting common unix priniting that is across from speech-dispatcher,,,across from the pulseaudio it says starting like wis DCE/RPC Endpo,,,all this time computer blinks,from the computer programing stuff to white lines,,,tryed all of what was posted to me the first time around with this promlem,,,the only thing i don't know how to do is "memory check using the boot menu item",,,also i could be working online and or off line computer will click off by it's self and blink on and off from computer programing stuff to white lines,,,also i do not know how to cut,copy,and or paste need to know how to do the cut,copy,and paste