Computer shutsdown.. So many have tried and so many have failed to fix..

[Cannonballz]

Myself included....
Computer= HP Pavilion Slimline desktop S5113 w-b
In short, Computer came with vista. I upgraded to win 7 (download). Everything was fine. Now I did not "activate" it within the 30 day grace period because I was away at the time..Duh!!! So when I got back my computer would shutdown automatically. Sometimes in 1 minute, 15 minutes or 3 days. I set it back to vista manufacturing setting. reformatted it.. completely wiped out. but it still shuts down out of nowhere.. all fans are running.. I changed power cords. I swapped ram cards. Still the same.. I even tried a completely different operating system(Linux) Same Problem.. It just closes all running programs and saves settings and shuts down. (No Blue screen of death) Then I turn it back on and it does NOT even say your computer was not shutdown properly. It just starts up normally. Like nothing happened!! When it runs, it is flawless!!! Of course I went into the power management and so forth and indicated to NEVER shutdown etc.... I'm just guessing it was related to the 30 day activation I missed. I've tried every registry program u could imagine.... Following that I went to the hardware.. I removed and replaced the lithium ion battery... nothing....It seems that when I am installing a different Operating System, that I could leave it on one of the steps involved, without hitting next, and the computer will stay on for good, it never shuts down during any installation but that seems dangerous in case it is a heating issue. Even with the Linux install disk, there is an option to just try it without installing it. So I''m basically running my computers operating system from a disk(not my hard drive) and it still shuts down.
Does ANYONE have any idea's???? could we use cross-loop or something for u to investigate.. Any programs you could recommend?? Besides Ccleaner, reg cure, reg mechanic.. Please man, This computer means A lot to me and I took great care of it but I just made a STUPID mistake...
Any help would be greatly appreciated!!!!!!!!!! Sincerely Jay

[Steve R Jones]

Heat, buldging caps on the mobo and a failing power supplys are the three main culprits to random ****downs.

[AllGamer]

i do agree chances are most likely a defective power supply (PSU)

just over the weekend i had to replace my server PSU, it was working fine for the past 2 years, but it was constantly overloaded.

it was simple to find out as i removed devices connected to it, it started working more and more stable, but as soon as i hook everything back up, it goes crazy again.

so replaced it with a brand new Corsair 1200 watt PSU, now all the 18 HDDs can run without killing the PSU

[Ol'Tunzafun]

It just closes all running programs and saves settings and shuts down.

A failing PSU will not close programs and save settings; it's receiving a shutdown command from somewhere. Is it running on a UPS? If not, I would try resetting the BIOS Setup to default settings, or even a BIOS flash if necessary.

[Rocketmech]

The last HP Slimline pc I worked on used a proprietary power supply, a mini 20 pin ATX connector, so testing with another power supply may be difficult.

The power button is a possibility. Check the Power Options in Control Panel, set the Power Button to "Do Nothing" . Also, its real tight inside the case, so look the button and wiring over to see if they are rubbing something causing it to trip the power signal. It will be hard to trace the wiring ( ribbon cable if I remember right) so you might need to remove it to inspect it. If the power button doesn't seem like it's popping back out after depressing it, then that would be a sign it may not be working correctly.

[Ol'Tunzafun]

set the Power Button to "Do Nothing"

That's an excellent suggestion.