Root Cause Failure Analysis Fail

I just finished setting up 10 laptops for new managers.  I hate this process, but it is much faster now since I figured out how to get one exactly right and then clone a disk image onto a usb hard drive.  I can then boot the new computer with a recovery disk and apply the disk image.

Anyway, there was something wrong with two of the installations.  Symantec had server issues all this week and two of the PC's simply would not sync with their servers, probably because I set them up at the heights of their issues.  So I had to pull them out, and do the uninstall-reinstall thing on the virus software.

But the very first laptop did not work -- it was coming on but its screen was blank.  I pulled another out of the box.  Same problem.  And again.

Panicking I changed the power supply, checked the power outlets, and everything else I could think of.  I finally called Dell in a rage.

Before they could really even pick up the phone, I happened to tilt the computer.  The screen came on.  I lifted it up in the air.  Worked fine.

I finally figured out that I was sitting the laptop on top another closed laptop (of the same model) I had been working on.  The bottom laptop was powered down, but it turned out that something was causing the laptop on top of it to have its screen not work.  I can only guess it was some magnetic thing from the battery charging apparatus, since that was the only thing that was likely energized in the other laptop.

Anyway, problem solved but I never would have guessed that stacking laptops would make them not work.


  1. Mike Powers:

    My favorite "weird tech support story" is one where a user could log in while sitting down but not while standing up. The issue was repeatable and demonstrated to tech support. Various theories were proposed about cables being kinked, connectors being pulled, interference with other computers, but eventually somebody noticed that two of the key caps on the keyboard had been switched. The user was a touch-typist while sitting but not while standing, and when doing hunt-and-peck they would enter the password wrong.

  2. disqus_00YDCZxqDV:

    Seriously? You are creating problems for yourself.

    Dell - the worst laptops money can buy with the worst support in the industry. It's such a false economy. Buy Lenovos instead. I have a stack of them from the late 90s when they were IBM and they all still work. It's a one-off cost, and if they are more expensive than Dell, in my opinion it's worth it because you can just give them out and forget them.

    Symantec? Are you serious? It's not 2002! They sell bug riddled bloated crapware to people who don't know any better. Save the money and have your users throw salt over their shoulders before using their computer. It would have the same effect as running Symantec. The most important thing you can do is make sure your users are not administrators of their own machine so they can't install anything. Also, have automatic windows updates turned on.

    If you must use AV software there are plenty of solutions like Spybot S&D and Kaspersky that do a heck of a lot better job than Symantec.

  3. Monsyne Dragon:

    I can tell you why this happened. Many laptops use a magnetic switch to tell if the lid is closed. If it is, they turn off the screen.
    The switch is just a reed switch in the body of the laptop activated by a small permanent magnet in the lid.

    When you stacked the laptops, the magnet in the bottom laptop's lid activated the switch in the top laptop, making it think it's lid was closed.

  4. Not Sure:

    "stacking laptops would make them not work."
    Same thing happens with cars.

  5. eburtonlab:

    One of my favorite troubleshooting stories involved a simple doorbell circuit. Folks kept complaining to my friend that the doorbell wasn't working. The first time it happened my friend went down into the basement to examine the doorbell unit -- a very simple transformer, couple of relays, screw terminals for the wires leading to the switches and annunciator. Everything seemed to be working fine; he shorted out the switch terminals and the bell rang; went back upstairs and tried the front door button and the bell rang; same with the back door. Everything was fine for a few days, and then someone else complained about the doorbell not working. Same deal: go down in the basement to check, and everything works. About the fourth or fifth time it happened, he was convinced that someone was playing a prank. He started checking the doorbell circuit every day, and it was always working. People stopped complaining, and everything seemed fine, so he eventually gave up.

    One day, on a whim, he tried the doorbell button at the front door as he was leaving the house. Nothing. No bell. He ran down into the basement to check the circuit. It was working fine. Went back upstairs to check the front door again and the bell rang as soon as he touched the button. There was no one else in the house but him.

    Eventually he pieced it together. The problem had started not long after the basement had been cleaned up. Someone had moved the doorbell circuit, and plugged it in to a different outlet. An outlet, it turned out, that was *switched* -- that is, it was connected to the same switch that turned on the lights in the basement (which were generally left on at all times). The doorbell would work fine, until some energy-conscious soul wandered by and turned off the basement lights, cutting the power to outlet -- and the doorbell circuit. When someone inevitably complained about the doorbell, my friend's first (anti-Pavlovian?) response was always to go down into the basement, turn on the lights (which turned on the doorbell circuit), and check the now-working circuit. The very act of observing the circuit affected its operation, temporarily "fixing" it, making it literally impossible to observe the fault.

  6. Craig Loehle:

    I left for work and my wife called that I left the garage door open. It was bitterly cold, below zero. next day as I backed out and started to drive off, I looked back to make sure I closed it, and saw it opening again. I went back to look. Moisture from the cars in the garage had condensed on the bottom of the opener, making a fractal pattern that was shorting out the opener. Had to use manual opener until warmer conditions a few days later.
    The small fridge at my office was interfering with the modem box right next to it causing fax and phone problems. Cable guy moved the box and problem went away.

  7. Mike Powers:

    hehehehe that is basically the plot of a joke in "Christmas Vacation"!

  8. Mike Powers:

    The best antivirus is to not be connected to the internet.

  9. Matthew Slyfield:

    Holy Heisenberg Batman.

  10. Matthew Slyfield:

    You can also turn that feature of on most laptops. Allows for running a laptop on a docking station connected to an external monitor without leaving the laptop open.

  11. Just a thought:

    Heisenberg? Don't you mean Mischievous Murphy? He's the one with the "certainty" law. ("Anything that can go wrong,....")

  12. Matthew Slyfield:

    No, I mean Heisenberg, as in the uncertainty principle that says in part that the process of observing things changes them. As in the doorbell worked when ever the doorbell circuit was observed.

  13. disqus_00YDCZxqDV:

    definitely if you can force the user to go via a corporate VPN and allow only intranet sites to be accessed that is the way to go.

    My wife has a Dell laptop from work, and she just came home and plugged it in. For no reason it suddenly started making a loud buzzing noise, forcing her to switch it off. "It does that all the time" she said.