Why does my computer randomly reboot without warning?

My computer has developed a strange problem in restarting itself... When the computer is first turned on in the morning it will restart itself or freeze instantly... If i keep rebooting or allowing it to restart, It will go a little further in the boot process until it eventually reaches the desktop. After many restarts it eventually runs fine. If I should restart the computer for any reason while it's up and running it has no problem in completing its booting process. Problem seems to only happen when the computer has been shut off for 30 minutes or so.

Computer shuts down every 25 mins. while playing solitare ; sometimes more often ; the screen that allows restart options is presented "sometimes" not everytime ; taking to the shop "again" Monday . it only occurs while playing solitare "KingSol". E Mail and E Net are okay . Salohcin

hi Leo. i have a computer that loves to randomly restart itself. it is not over heating becuase i have alot of fans and there is no dust. also it loves to randomly show the blue screen of death. i tried everything posseible to keep this from happening. i am running windows media center eddition with the latest pack. thanks

hi im having some issues with my computer, sometime my desktop just reboot by itself, sometimes after 5 min sometimes after a couple of hours, after the first reboot it keep doing again and again until i just shut the power, at this moment the case is open so is not the temperature, i check the memory ram, remove 1 of them and use just one memory then i switch the memory and the same, update the BIOS on my MOBO, reinstall the windows, check the power supply using a power supply tester, plug the power supply tester, turn or the power supply and leave it like this arround 1 hour and it work fine but when i connect everything else and the problem keep comming, on the BIOS show me the internal temperature at 46 C and the CPU temperature at 38 C, remove all the hardware and leave just the HDD and one cd drive but nothing, remove the CPU fan and clean it, add more cooling paste on the CPU... i dont know what else can i check, PLEASE I NEED SOME HELP!!!!!! who can give me some ideas about how to fix this??? im using an intel mobo G35EC with the cpu E8400, 2 Gb ram 800 mhz, the video card is an XFX 9800 gt, the power supply is 550W, changed the CPU fan a while ago...

I'm having the same problem. However i've found out the solution lies on the ram. If i remove one ram out, it's fine. Although my motherboard max ram is 2gb, it can't take 2gb. 1gb + 512mb works fine, but not 2Gb im not sure why but hey it works :(

I had posted a few months back about my computer restarting itself... Turns out it was a motherboard issue. I noticed (by accident) that the capacitors had starting crapping out. Replaced the mb and no more issues. an Ebay $39.00 fix

My computer reboots without warning. However, if I change the electrical source (different outlet in another room) it works fine. If I put an extension cord onit using the outlet that workd it shuts down and restarts again. An electrician and the power company has checked the power and said all is fine. I then plugged a different PC into the original outlet and it works fine.
HELP!

hy. my computer is restarting without reason. it appears a black screen and restarts. I dont know what to do. I'm in the middle of something and the ps is restarting. i cant even save what i'm doing. please help

My pc was also rebooting without warning. I guess it started after installing MS Visio 2010 Beta. I only had XP SP2. Office 2010 requires SP3 for XP. So installing sp3 solved my problem.

i have this e-machine that when it boots up the pc goes into a self diagnosis pc display settings correct