Fixing Odd Mac Mouse or Trackpad Behaviors & Random Clicks
The mouse and trackpad are pretty essential to desktop Mac users, so if the input devices start acting up with mystery clicks, clicks not registering, erratic motions, and other weird behavior, you have good reason to be frustrated.
First, Check the Hardware
It should be noted that such problems are usually not a software issue with OS X, instead it may be something much easier to resolve and diagnose with the physical hardware, like any of the following:
- A piece of lint or junk stuck in the optical light
- Crud and gunk buildup on the tracking surface
- Wireless Bluetooth device battery levels diminishing to the point where behavior is not registered properly, requiring new batteries
- Bluetooth devices randomly disconnecting themselves, usually requiring a quick battery swap and reconnection
If you’ve covered each of those more obvious avenues and still run into issues with a trackpad or mouse acting weird, you may want to try trashing the preference files and rebooting the Mac, forcing them to be rebuilt. This often resolves odd issues that have no apparent explanation, and it can be done rather quickly.
Troubleshooting Erratic Mouse & Trackpad Behavior on a Mac by Ditching Input plist Files
It’s unlikely something will go terribly wrong with this process but it’s always a good idea to backup a Mac before deleting any important files and preference files anyway. Do that with Time Machine or your back up method of choice, then you’re ready to go.
- From the OS X Finder, hit Command+Shift+G to bring up “Go To Folder”
- Enter the following path: ~/Library/Preferences/ and choose Go
- Locate the following files manually, or use the Search box in the upper right corner and narrow down for ‘driver’ to find them – remove the ones that are relevant to your issue:
- Drag the appropriate files* to the desktop to make a backup of them, or just delete the files* if you’re comfortable with that
- Leave the user Preferences folder and reboot the Mac
com.apple.driver.AppleBluetoothMultitouch.trackpad.plist - Magic Trackpad
com.apple.driver.AppleBluetoothMultitouch.mouse.plist - Magic Mouse
com.apple.driver.AppleHIDMouse.plist - wired USB mouse
*Note: you can get more specific if you want, like only deleting the AppleHIDMouse.plist file if you are only using a USB mouse, or only removing BlueToothMultitouch.mouse if you only use a Magic Mouse, or you can ditch all three if you’re using all of them.
With a reboot the Mac will rebuild the preference files for the input devices that are in use, and, hopefully at least, the erroneous tracking or clicking behavior will be resolved.
Remember, by ditching the preference files you’l lose customizations made to things like tracking speed, alt-click, gestures, and clicking behavior, so you’ll want to go back to the appropriate System Preference panel and reconfigure any specifics you had beforehand.