I now have reason to believe that the problem with my laptop this time around isn't a flat-out defective mainboard. Rather, it seems that the DC input jack came loose from the back of the unit: it'll provide power if the plug is held in at an angle. I find it interesting that this very thing happened to my old HP laptop twice before I settled on buying a considerably more durable port replicator to remedy the issue.
For now, I still haven't got a clue whether or not I should be trusting the machine to work any further. I'm curious to hear other people's thoughts to this matter: is it best to leave the machine be and continue using it, send it in for repairs, or give up on it?
In other unrelated news, I found myself playing Call of Duty 4 multiplayer on an Xbox 360 earlier today. CoD4's gameplay is quite intuitive, and its graphics are pretty darn good even when viewed in split-screen on a 480i CRT TV. Grenade explosions are carried out in a neat way: while most games simply produce an explosion with lights and shrapnel, Call of Duty takes things one step further and introduces disorientation. The controls become much looser and wobbly, you're temporarily blinded, and a sound is produced that's similar to the ringing in one's ears experienced after the shock of a loud noise. Weapons are pretty interesting: in addition to the classic "nuke" weapons such as RPGs and grenade launchers, the game also features guns that will penetrate walls of certain thicknesses, and the ability to call in an airstrike, remotely, on an enemy's position once visual contact is achieved. For reference, the last two were what inflicted the largest amount of kills on me. I couldn't understand the aiming facilities: using the L trigger to aim results in an extremely precise shot regardless of the weapon you're using (including such random-fire weapons as assault rifles), whereas opting not to target even at point-blank range results in your bullets flying everywhere but at your enemy. There's also an interesting feature upon death, provided you're shot down and not blown to bits by a grenade or similar weapon, known as "Last Stand": you're given the option of either shooting at your enemy with your sidearm (usually a pistol) in a last-ditch attempt to kill them, or alternatively you can take the "Coward's Way Out" and kill yourself before the five seconds are up. Gruesome, yes, but a pretty cool experience overall.