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  1. #1
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    No way to stop PC rebooting

    No idea where to write this one ... maybe someone can redirect me .

    I have a PC that reboots itself no matter what I do. After lot of painfull tests this is what I found:

    * The PC does not reboot if the LAN cable is not connected.
    * As soon (15/20seconds) as the LAN cable is reconnected, it boots.

    An Ethereal trace shows a series of
    NBNS Name query NB BRN_6F2D1D<00>
    messages just before the PC reboots, coming from diferent PCs on the LAN and directed to 192.168.1.255

    This seems to be a request for a shared Brother printer USB connected to the rebooting PC ... but somehow strange because the PC reboots itself even when all other PCs on the LAN are switched off (and of course I cannot get an Ethereal trace in that situation ).

    Any idea? Even a forum where this can be posted would help, I don't know how to deal with it.

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  2. #2
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    Re: No way to stop PC rebooting

    Most modern BIOS have a wakeup on LAN feature, is that enabled?

  3. #3
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    Re: No way to stop PC rebooting

    I have tested it both with LAN enabled and disabled. It reboots on both situations.

    We would like to have LAN reboot enabled because this particular PC needs to be rebooted early on the morning by some user on a diferent room, and to avoid him going to the PC room. But as I said, it reboots even with LAN reboot disabled.
    The software we use to wake up the PC sends a series of UDP messages that we can easily identify on Ethereal and that are NOT present at all when we test the reboot problem.

    Thks
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  4. #4
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    Re: No way to stop PC rebooting

    What is the time frame of this 15 to 20 seconds. Is this after Windows is fully loaded and just sitting there? What kind of processes are running in the background? Possible trojan?
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  5. #5
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    Re: No way to stop PC rebooting

    Safe mode? w/Networking? Be specific
    David

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  6. #6
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    Re: No way to stop PC rebooting

    Quote Originally Posted by PeejAvery
    What is the time frame of this 15 to 20 seconds. Is this after Windows is fully loaded and just sitting there? What kind of processes are running in the background? Possible trojan?
    Maybe I didn't explain it correctly.

    I shut down the PC. It closes orderly. All lights off.
    Then, after a period of aprox 15/20sec it reboots itself.
    There is nothing running in the background because the PC is stopped.
    McAfee doesn't find anything wrong on it (neither on other PCs on the LAN).

    If the LAN cable is disconnected, it doesn't reboot.
    If the LAN cable is connected, using Ethereal on another PC on the LAN, shows the NBNS protocol messages just before the PC reboots.
    What makes me crazy is that it reboots when no other PC on the LAN is on , so I cannot stablish a 100% relationship with the messages and the rebooting.

    Quote Originally Posted by dglienna
    Safe mode? w/Networking? Be specific
    Sorry dglienna, I don't understand what are you asking me.

    Thks
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  7. #7
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    Re: No way to stop PC rebooting

    Hit F8 as it's booting, and try first Safe Mode, then Safe Mode with Networking.

    You should have no problem without the networking, but might have with it.

    This would indicate a driver conflict.
    David

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  8. #8
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    Re: No way to stop PC rebooting

    This has nothing to do with drivers. S_M_A was completely correct. You need to double check your BIOS settings.

    EDIT: Don't disable the LAN. There is a feature to disable "Wake on LAN." That is what you need to turn off.
    Last edited by PeejAvery; June 9th, 2008 at 05:02 PM.
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  9. #9
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    Re: No way to stop PC rebooting

    Based on the problem description, I'm still not sure that the machine is rebooting prior to starting up in Windows or while Windows is booting. If the later, try running in safe mode, look at the Run keys in each hive of the registry (Software/Microsoft/Windows/CurrentControlSet/Run). Make sure that there isn't a process set to run that is causing the reboot. Also, a Windows service can be set to reboot on error, so perhaps one of the services is faulting?

  10. #10
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    Re: No way to stop PC rebooting

    Quote Originally Posted by Arjay
    Based on the problem description, I'm still not sure that the machine is rebooting prior to starting up in Windows or while Windows is booting. If the later, try running in safe mode, look at the Run keys in each hive of the registry (Software/Microsoft/Windows/CurrentControlSet/Run). Make sure that there isn't a process set to run that is causing the reboot. Also, a Windows service can be set to reboot on error, so perhaps one of the services is faulting?
    The PC is not rebooting "while Windows is booting" or "prior to starting up in Windows".
    Windows is up and running, the PC is working with no problems. Then, when we finish our working day, we shutdown it normally. It shutdowns without problems ... and when we think we can go home and take a beer calmly ... the PC boots itself as if someone hit the start button. But obviously no one did!

    I don't think a service is rebooting on error, this would reboot the PC at once, but it's clear that it takes some time to do it. I mean, all lights are off for a while, it's not a smooth and inmediate reboot.

    I suspect some other PC is asking him to boot (asking for a shared printer maybe?) ... but the incredible fact is that NO other PC on the LAN is on at the time. It boots itself even if there is no one else on.

    Will double check all BIOS settings ...

    Could it be a LAN printer that wakes up this PC? It's a multifunction (so, FAX) printer and we cannot stop it!
    Could it be an USB printer that wakes up this PC? It's defined as shared, and maybe it want to be alive?

    Thks for all your answer, will continue to investigate. Maybe I could have a PC on, with Ethereal but without the shared printer defined, so no request from it.

    Last edited by DeepButi; June 10th, 2008 at 03:11 AM.
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  11. #11
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    Re: No way to stop PC rebooting

    OK. I was wrong on one point: Power on by PCI card is enabled.
    Disabling it stops the PC "powering on".
    My fault, I was confused with the "3rd booting device: LAN/disabled"

    Anyway, my question remains ... who/what is powering it on?

    We want to be able to power it on remotely, but we don't want it to power on by itself without us giving the order to do it.

    What can cause it to power on?

    Thks
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  12. #12
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    Re: No way to stop PC rebooting

    What PCI devices are present? Maybe a PCI graphics card attached to a powered plug & play monitor can cause PC to boot? Have no clue actually just guessing at the moment...

    Try disconnecting PCI devices one after another.

  13. #13
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    Re: No way to stop PC rebooting

    Quote Originally Posted by S_M_A
    What PCI devices are present? Maybe a PCI graphics card attached to a powered plug & play monitor can cause PC to boot? Have no clue actually just guessing at the moment...

    Try disconnecting PCI devices one after another.
    It's a standard PC, nothing installed on our own. How can I identify PCI devices? No PCI devices show on Control Panel>>System>>Devices manager.
    We are using W/Vista.

    I tried setting the Ethernet card Wake up type from OS Controlled to Magic Packet. In theory this should only allow Magic Packets (FF FF FF FF FF FF followed by 16 times the MAC address) to wake it up .... but it still powers up without anyone's intervention.
    Still have to test with all other PCs off ... this will have to wait until late, I cannot stop our people at working ours .

    All my tests show the NBNS messages just before the PC wakes up, but I don't know what they mean, neither how can I prevent the PC to wake up on them .

    Thks for all your answers.
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  14. #14
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    Re: No way to stop PC rebooting

    Once again...The only thing that can cause a sleeping/shutdown computer to turn on is Wake on LAN. You will notice that even though your computer is turned off, the light(s) on the NIC still can flash or be lit up.

    Find the Wake on Lan setting in the BIOS, and disable it.
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  15. #15
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    Re: No way to stop PC rebooting

    Quote Originally Posted by PeejAvery
    Once again...The only thing that can cause a sleeping/shutdown computer to turn on is Wake on LAN. You will notice that even though your computer is turned off, the light(s) on the NIC still can flash or be lit up.
    Find the Wake on Lan setting in the BIOS, and disable it.
    Thks PeejAvery. Maybe you didn't read all my posts (easy, there are too many ). As I stated previously, yes, you are right. Wake on LAN is enabled and we want it to be enabled because we want to wake up the PC.

    What we don't want is it waking up by itself. So I'm trying to discover who/what wakes it up.

    Thks
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    The best conversation I had was over forty million years ago ... and that was with a coffee machine.

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