About two or three seconds after my computer starts to boot up, it suddenly shuts off again. I dust my computer (and computer desk) daily in very effective fashion, so I know dust isn't the trouble. I thought overheating was the problem, but the computer doesn't feel unusually warm, have dust in the fans, et cetera. Every single chord or wire is plugged in securely, and my computer has no deadly bits of malware, spyware, or any other potentially harmful problems.
Is there anybody who can help me with this problem? If so, it would be a blessing!
Likely the heatsink not making proper contact.
About two or three seconds after my computer starts to boot up, it suddenly shuts off again. I dust my computer (and computer desk) daily in very effective fashion, so I know dust isn't the trouble. I thought overheating was the problem, but the computer doesn't feel unusually warm, have dust in the fans, et cetera. Every single chord or wire is plugged in securely, and my computer has no deadly bits of malware, spyware, or any other potentially harmful problems.
Is there anybody who can help me with this problem? If so, it would be a blessing!
My hubby's laptop does something similar. If I have just turned it on, or switched user, the screen suddenly goes to sleep so I have to press any button to wake it up again. It only does it at those times, never once I actually start using it. 
It is an Apple. What is yours?
I've got that with my computer sometimes too, it's just that I push in the button too far. It starts only when you push it in lightly, I don't know if that'll help you anything?
Does it alsways fail at a certain point? If so, when does it happen(i.e.during the POST, or when booting the OS, or when the OS is loading programs?)
I got my computer sent to a Best Buy. It turns out that the Motherboard is shot AND the start button has issues.