I've got an old Dell Latitude D610 running XP Pro that's given me six years of trusty service, though it might've finally met its end.
About a week ago I was using the laptop for mundane tasks (reading a .pdf, listening to some music, and on Gmail with Chrome), nothing unusual, when everything froze up. No blue screen, but no sound and no movement, though the screen was still up and running - your typical freeze. This was odd to me as I've rarely had any freezing moments on the laptop, but there it was. So I hard restarted, which is when the problem began in earnest.
Since that point (with one exception that I'll mention in a moment), every time I press the power button, the laptop powers on, the screen does not light up, and after a three-or-so second hang it powers itself down. I never see anything on the screen. I've done this quite a few times at this point, and the only exception was that once, for no reason I can account for, it booted normally and got to the desktop, but then froze up again while startup programs were still loading. Same deal since then.
My initial thought is a RAM issue, but after looking around online, it seems that a couple other people have had this same problem where it was a fried mobo or even a broken HDD. I've got my fingers crossed for RAM, but does anyone have concrete ideas?