How can this happen?

  Chas 22:25 18 Mar 07
Locked

Recently my PC has started to exhibit a very strange behavior. After a totally normal session I shut it down, it powers off and then, after betwen 10 and 30 minutes, it starts up on its own and presents me with the usual XP login screen. How can this happen? What is waking it up (indeed - how can it be aroused from a shut-down state?) - and should I be concerned?

All help and advice gratefuly received - Chas.

  Giggle n' Bits 22:30 18 Mar 07

this could be Wake on Lan in the BIOS or wake on x something in the BIOS power managment settings maybe is waking up your machine.

I have never known a virus to actually swith on a machine. Have you got you mahcine on a wirless network ?

  p;3 22:32 18 Mar 07

strangely another thread is running on here with similar problems ; may one ask what av and other protection programs you have on there and when they were last fully updated and run?

and, if it were my machine I would be concerned until I knew why this was happening or what the cause was and if the cause needed to be removed

also; BB or dial up etc

also; I presume you leave the power on?

  Chas 22:45 18 Mar 07

I do not have my machine on a wireless network. I run Norton antivirus daily (quick scan) and weekly (deep scan). My subscription is current. In addition I run Windows Defender daily. I also have a hardware firewall (BT Home Hub). In addition I run Zone Alarm (free) firewall software. I am on BT Broadband.

Whenever this has happened the power has been left on (clearly it couldn't restart if the power ws off). It doesn't happen if I hibernate the PC - only if I shut it down. Nothing appears to be running when it restarts. (Not that this means nothing IS running or HAS BEEN running - only that I haven't been able to spot what is).

  p;3 22:53 18 Mar 07

it's not Norton trying to get its updates is it?

also; you could do worse than run

click here

click here

click here

and see if any of them throw up anything

  woodchip 23:08 18 Mar 07

It's the BIOS turning it on, check what is enabled in power management

  Spark6 23:39 18 Mar 07

I've just picked up this thread and I fail to get my head around how the BIOS can override the 'power on' switch of a computer. Surely, this machine is NOT shutting down correctly.

p3: no false positives or scares please.

  villageidiot 00:03 19 Mar 07

How are you performing your "shut down" - with the "Turn off" button or the "Standby" button?

As woodchip points out, if there is no power from the PSU to the MB, then the only power on the MB is to the BIOS, so something in there is switching it on.

Unless - The remote lock/unlock on my car is triggered if I park in certain places. It only happens in certain places, so I assume it is caused by a concentration of radio waves in these places. Also, my computer trills away every time my mobile phone responds on being interrogated by the network. Could these signals be triggering your computer into action? Is there an amplifier on the MB connected to the PSU that could be triggered? Over to someone with some knowledge of the electronic circuit in a PSU.

  Giggle n' Bits 00:28 19 Mar 07

the other things could be a faulty Power case switch or a short in the PSU hotwireing the power on switch to motherboard.

Have a look in BIOS first under power managment like M8 Woodchip says, then test the PSU.

What brand of machine have you got? and if you have the model number this will help me and others to ident the system more deeply.

  laurie53 07:29 19 Mar 07

This has happened to me a couple of times, tho' not recently. I was able to tie it to switching on another piece of electrical equipment (non-computer).

Maybe a small spike? Freezer, CH etc?

Laurie

  octal 08:02 19 Mar 07

laurie53 has a good point, the switch is quite often a software switch and not strictly a power switch, in other words the power supply is always ticking over in the background. My computer does that.

Switch it off at the wall socket, problem solved and you'll be saving electricity by not having the power supply running 24/7.

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