Hi,
I'm using Linux Mint 16 KDE and I have a very strange problem. It happens often that the system thinks my meta key (Cltr, Alt or them both) are still pressed, while they are not. This means that if I click on a UI element or if I use the mouse wheel, the result is not the intended one. To solve this, I have to press Ctrl and/or Alt (or both, since I can't know beforehand what is the "blocked" key) to get back to the normal behaviour.
Please note that:

• the accessibility option for "sticky" meta keys is disabled
• the problem happens quite randomly (but often)... I mean, I didn't find a way to reliably reproduce
• the keyboard is OK from a hardware point of view (I would say it's a software problem)

Has someone an idea of what might be going on?

Thanks in advance.

Hi there,

... with its support expiring shortly. You should consider upgrading soon.

I've seen this phenomenon from time to time, too. The reason this can happen at all is the way how keyboard information is transferred: Each time a key is pressed, the keyboard sends a so-called "make" code with the code of that key; and when you release the key, a "break" code with the same key code is sent. If for some reason the break code isn't recognized by the system, it kind of thinks the key is still pressed.

This happens sometimes when the system is very busy, or when the PS/2 or USB communication between keyboard and main system is garbled. However, you can't do anything about that.

[X] Doc CPU

Hi Doc, thanks for your help!!

Oh, yes, but apart from the fact that Linux Mint KDE 17 isn't ready yet, I want to upgrade only when the support period really ends (i.e.: no more security updates), since stability for me is more important than upgrades at all cost.

But this happens too often on my system, which is a very recent Haswell i5 processor with a SSD. The problem is so annoying that it's hardly believable that it's "normal".
The feeling is that as soon as I start some "complex" key combination sequence (like Alt+TAB, Ctrl+Shift+V, etc.) if this is done "quickly" the chance to get this problem is high []

Hi there,

that's a very decent attitude. :-)

No, if it's really that frequently, it is far from normal. So we have to try to narrow it down.

Have you tried to use a different keyboard? - If the problem disappears then, it seems to be a hardware thing.
Does this effect occur if you run a Live system off a CD or USB drive? - If not, there may be an issue with your OS's keyboard driver.
Apart from that, I'm running out of ideas ...

[X] Doc CPU

As a first attempt, I'll try with another keyboard and let you know, thank you.

are you by any chance running linux mint kde on a (virtualbox) virtual machine?

No, it's a physical laptop.

Ah, a laptop, I'm not sure whether it would help but I would be tempted to try to use the built-in keyboard and see how that goes. I'd be tempted to think that the machine is somehow confusing the two keyboards (I'm assuming you have plugged in an external keyboard). If this is the case, and there's no other way around it, it may be worth looking into disabling the built-in keyboard somehow.

Unfortunately, it's not the case. The problem actually happens with the built-in keyboard. I'm going to try with an external one, as soon as possible.

Just a note for anyone encountering something like this.
The problem seemed to happen whenever I inadvertently hit the touchpad while typing some "complex" key combination (involving a meta key), although I had the option to disable the touchpad while typing for X seconds enabled.
I never understood the actual cause or the real fix and honestly I'm not sure if using an external mouse and keyboard could completely prevent this from happening or not (I never had the chance to thoroughly test that).
However, after upgrading to Linux Mint 17 KDE, with a much similar configuration (I would say, the same one) I've not experienced this problem any more yet.

Thanks again to anyone for the help.