Mac thinks alt/option key is always held down

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Level 1

31 points

Mac thinks alt/option key is always held down

This problem has happened twice on this iMac in the last two weeks. The first time it didn't disappear until I reinstalled Yosemite fresh. Now it has randomly done it again. Here is the full deal.

iMac 27" late 2009, 12 gb of RAM, Wacom Intuos 3 tablet, external OWC Mercury Elite Pro FW800 2 TB drive, Mac OS X Yosemite 10.10.2, Apple Wireless Keyboard (came with iMac), Microsoft Wireless Mobile Mouse 3500. The Mac goes along fine, then suddenly all type input from the keyboard is scrambled looking. However, the reason becomes clear when the Keyboard Viewer is opened: the Mac thinks the alt/option key is pressed. If the keyboard is powered off, taken away from the Mac, and linked up to an iPad Air 2, it works perfectly, so it isn't the keyboard.

I am at my wits end. After years without a Mac (but with an iPhone and an iPad), I expected not to run into this kind of PC-style inexplicable nuttiness. Maybe someone here can explain this phenomena and tell me whatbI am doing wrong.

iMac, OS X Yosemite (10.10.2), 27" Late 2009, 12 gb RAM

Posted on Feb 5, 2015 6:07 PM

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Answer 1

Glenn Millam Author

Level 1

31 points

Feb 15, 2015 2:40 PM in response to CarlAVII

I determined the problem, and in the hopes that some of the other people who I have read on the internet who have suffered this issue can gain some better understanding of it, I offer my solution.

The problem was the Wacom Intuous 3 tablet and its driver. I am not sure if it is a hardware issue, or if it is a driver issue. The driver was the latest at this time of posting. The problem was that the set of small buttons in the rectangular area at the left top of the tablet have been mapped, by default, to keystrokes including the alt/option key. The tablet assumed that the button was pressed for this key and would not release it. The solution was to open the Wacom driver in System Preferences and remap the button to a different key (in my case, I remapped it to nothing, as I didn't use the button all that much). I don't remember if it needed a restart afterwards (I doubt it).

I have noticed that many of the people who suffered this issue have Wacom tablets. This suggests a driver problem, but it may be that the button it uses is faulty on this model of tablet. I can easily see this being a problem with any peripheral that has buttons capable of executing keystrokes, such as specialty mice. For those who do not have a Wacom tablet, or some device capable of mapping buttons to keyboard keys, I suggest trying Allen's solution above. That procedure can cure a lot of Mac problems.

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