Um, first, specs, I guess: NVIDIA Vanta/Vanta LT Antec SL300S 300-Watt Power Supply (I think) Case looks like this: http://www.antec.com/Believe_it/product.php?Type=Mg==&id=Njcw Samsung SP09802N, 80GB. No clue about the rest, instruct me on finding out? Ok, so here's what happened: It was running fine, and then it shut off. Descriptive, I know. The first time it crashed was on Saturday after a Realtor came in and had a look around the house. I was on it for a couple hours, and then I shut it off for dinner. I went back on, and I think about 10 minutes later, it shut down. (By shut down, I mean sudden, no warning. Power outage kind of thing.) I think I waited a while, and then I tried it again, and it worked for the rest of the night. The next day, and after that, it got worse, lasting anywhere between 2 seconds (lol, died half-way through the start-up beep) and I guess 3 hours. Now, today, the longest it would run is about 30 seconds. I have no idea why it's doing this. Help with diagnosing the problem is greatly needed. For a little background information: This is not the first time it has randomly shut down like this. Before, at night, I would shut off the power bar for the computer because all the little lights irritate me. (I love total darkness when I'm sleeping.) The next morning, it would run for a little while and then shut off, unless I waited after turning on the power supply again. I have since stopped doing this, so, unless it's coming back to haunt me, I don't think it's the problem, even though the symptom is the same. Actually, the last time I ever did that was not-so-recently now (about a couple of weeks ago), and when I turned it on, it, very nearly literally, exploded. The first morning, I heard cracks and snaps, and I figured they were coming from somewhere else (no hearing aids on in the morning), and they stopped and it ran fine. The next morning, I had my hearing aids on this time, and I realized that the noise was indeed coming from my computer. I peeked inside it (I leave the one side off because the fan gets too noisy with it on) just in time to see a horrific flash accompanied by an especially loud crack. I can't remember exactly what I did (I was too startled to remember) but I think I switched off the power bar to turn my computer off (it stopped loading, but was still running), turned the bar back on, but didn't touch my computer for a couple hours. o.o In case you're wondering, the flash came from somewhere in the top right corner of the inside of my computer, which I now realize is where the plug connecting the motherboard and the power supply is. (I have since had a peek at this, and it seems completely undamaged. Another possibility why this is happening (the other one being something is shot) is a virus. Well, I honestly don't know. Do viruses randomly shut off your computer? I do admit I probably could use an upgrade in terms of anti-virus, I currently only have/had the free Avira. My brother suspected over-heating, but it crashed after 2 seconds this morning, after it had been off all night, and nothing ever felt hot in there before, and I leave the side off. Um..... that's all the relevant incidents/information that I can think of. I'll gladly try and get you more information, since I realize this probably isn't enough, especially in terms of the specs. Just realize that if it requires running the computer, I'll be lucky to get 5 minutes out of it. If I had to guess, I'd say something is up with the motherboard or the power supply. So.... I realize that fixing this probably means replacing some parts, something I was planning on doing soon anyway. If anyone wants to suggest products, I need the input. I for sure want to replace the case. My current one will have the fan going nuts within 5 minutes of running, so I have to leave the casing off. Um, does the CD drive come/go with the case? And anyone laughing at that video card I have, I'm getting that replaced for sure, I think I already have a replacement, though. (My brother's, after he gets an even better one. His has HD, definitely a step-up - nay, a giant leap up - from mine.) Also, I might replace the motherboard or power supply, or both, so I need suggestions there. I have 1G of RAM and no idea if this is good or bad, and I very sincerely hope I don't need to replace my hard drive. Um..... that's all I can think of, but I'm probably missing something. tl;dr? My computer is shutting off randomly, it might be the power supply or motherboard, and I'm looking to upgrade.