Hot corners stop working

Wednesday, July 23

Some Leopard users have found that hot corners suddenly stop activating various features such as Exposé, Spaces, and the Screen saver, despite the presence of previously assigned settings.

Apple Discussions poster lostintrns writes:

"I set my system prefs under "Expose and Spaces" so that top left would start screen saver, top right would show spaces, bottom right would show desktop. It worked great yesterday, but upon startup today, hot corners aren't responding. I checked my settings, and they're exactly the same as they were yesterday, all correct, but hot corners won't work."

This problem seems to manifest itself in various ways. For some users, problems with Exposé and Spaces seem to be coupled with the dock no longer appearing, and for others only some of the assigned hot corners seem to work, whereas others do not. Sometimes hot corners will work intermittently and it takes several tries to get them to work. In some instances, this problem appears to be associated with the attachment of external displays, though not all affected users have been using external monitors.

Regardless of specifics, the problem lies with hot corners instead of the specific functions such as Exposé, all of which can still be enabled via alternative methods. As such, there may be two issues at play: one mouse driver related, and the other a problem with the hot corner settings themselves.

Fixes

Unplug the mouse and plug it back in Doing this will reload the mouse driver, and hopefully reset any problematic driver functions that were preventing hot corners from being recognized.

Restart the dock; logout and log back in Some users have attributed this problem to the Dock, and have found that restarting the dock will fix the problem. To do this, launch the Terminal (located in /Applications/Utilities) and enter the command killall Dock. Alternatively, logging out and logging back in should accomplish the same.

Repair permissions and restart the computer Similar to the first fix, restarting the computer will also reload the driver (and is the only option for laptop users). Doing this will also reload the hot-corner preferences; however, be sure to run a permissions fix on the boot drive before doing so to ensure preferences are properly accessible.

Temporarily reassign hot corners to something else Forcing the hot corner settings to reset by temporarily resetting them to functions beside the desired behavior will cause the system to reset the hot corner preferences. Test out the new settings and ensure they work then reset the hot corners to the desired functions. Users might also try to do this in safe mode (boot while holding the shift key) to ensure no other potentially intrusive software or drivers are loaded while these settings are being changed.

Feedback? Late-breakers@macfixit.com.

Resources