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Been using rarely my Lenovo G560 laptop and after long time of not using it I have noticed that touchpad stops responding after short while. Incidentally while trying to find the cause, after pointing on taskbar I've noticed swift tabbing in right direction between taskbar icons appearing as some key was stuck which is the case I reckon because when problem reappears and I press on directional right key, the scrolling stops for short period but then resumes. The bad thing is that it also happens in BIOS, not to mention Windows 7 boot screen and scrolls down, which leads me to believe something is faulty in keyboard keys or keyboard itseld because no key is stuck-pressed.

See this video of scrolling in Start menu:

Constant Scrolling Interferes With My Work

This laptop hasn't been used for over a year and I did not drop it. Should I take keyboard off and clean contacts? How to solve this?

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4 Answers

up vote 4 down vote accepted

It sounds like keys are "sticking down". Though in fact they don't really "stick down", but rather the electrical signals get a bit haywire. More likely if you've ever spilled anything on the KB, but can happen without, especially if the unit is rarely used.

If it's simply a matter of rare use then it's fairly likely that "exercising" the keyboard for a few minutes -- just punching all the keys repeatedly -- will improve the situation, and maybe cure it, at least temporarily.

Added: Keep in mind that most laptop keyboards consist of a rubber membrane over a printed circuit. Pressing a key presses the membrane against the printed circuit, and the conductive rubber of the membrane thus "completes" a circuit, allowing the key press to be detected. (In some cases the detection is capacitive rather than resistive, but the principle is the same.)

A big advantage to this scheme is that it's hard for the innards to get dirty (though spilling liquid on the keyboard can do it).

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Thanks, I think your advice helped to some extent to solve my problem. –  Boris_yo Feb 20 '13 at 16:41
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Seems like a defective keyboard with a stuck key/keys.

because no key is stuck-pressed

Just because the physical key is not pressed in does not mean the key mechanism isn't faulty and stuck.

It is possible that the contacts are corroded or that a foreign body (insect?) is shorting the contacts. Best way to clean keyboards (in my opinion) is by using a vacuum cleaner, which can suck out particles between keys. If you don't have that then instead blow air into it using a pressured air can. This may however send the foreign body deeper into the computer.

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The keyboard was not defective from start but it seems it got faulty without my intervention, at least so I think. Can you advise me what to do, what to clean maybe? –  Boris_yo Jan 23 '13 at 21:02
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If you still have one, claim it on warranty. I've had many laptop keyboards replaced, free of charge, over the years.

If it takes more than (carefully administered) soapy water and a soft cloth to get rid of dirt or grime, you'll get a better result from a replacement keyboard.

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@Daniel has probably given you the most accurate answer you're going to receive on a stuck key issue. Normally there would be a lot of software issues to check first, but since you said this also happens in BIOS, it's not the case.

Given the thin cable connecting the keyboard to the mobo and the length of time you said it sat for, component creep (ribbon) is a possibility, but highly rare.

The only possible options you have left are:

  • 1. Try resetting the default key bindings: Pressing Ctrl + Alt + fn (Windows key)
  • 2. Remove the keyboard, separate the keys from the the back-plate and clean it with rubbing alcohol.

    You can follow this video guide to remove the keyboard if you're unsure.

  • Unplug the laptop, pull the battery, and hold down the power for about 60 sec. This will discharge all remaining power in the laptop forcing all components to reset. When the laptop is restarted everything will form new default connections.

    If none of the things mentioned so far work, then get a new keyboard, because there is nothing left for you to try.

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    Thanks for advice. Concerning your solution of discharging all remaining power in components, do you think doing this prior to disassembling keyboard will work? Worth a try, isn't it? –  Boris_yo Feb 10 '13 at 19:59
        
    Me personally, I would say remove the keyboard, clean it real good and re install it. Like @Daniel already mentioned, the rubber boots beneath the keys tend to stick. Obviously if this ends up being the case and solving your problem then credit needs to go to Daniel. –  Josh Campbell Feb 10 '13 at 20:51
        
    What ended up being the problem? –  Josh Campbell Feb 11 '13 at 13:16
        
    I deemed your information had more to offer so that's why I rewarded you while Daniel's advice did not work for me in its entirety. However after a short while the problem corrected itself which I didn't expect it to and thought the only way for me would be to disassemble keyboard and give it a nice clean which of course luckily I didn't have to. So Daniel's advice proved to contribute to solution because I doubt keyboard would fix itself without me first "exercising" it. Hey if SuperUser allowed it, I would divide reputation points between you both. –  Boris_yo Feb 20 '13 at 16:40
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    It's all good Boris. Rep points mean absolutely nothing to me. I get my kicks from peoples' problems getting solved. Glad to hear it all worked out. –  Josh Campbell Feb 20 '13 at 22:28
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