Stop desktop difficulties dragging you down
QApparently at random moments, every couple of days, my wired USB Apple mouse stops working, and I can’t control my Mac any more. I’ve tried using a different mouse, but the same problem occurs. The only solution when this happens is to force a restart. I’m running OS X El Capitan 10.11.6. How do I fix this?
AIf your Mac has frozen completely – with the keyboard not working, and the clock stopped – this is a kernel panic, in which the operating system itself has ground to a halt. That should never happen, but some Macs running El Capitan, particularly versions 10.11.4 onwards, seem to be prone to sporadic kernel panics.
Old and incompatible extensions are a potential cause of this, particularly those that support ageing peripherals or ‘enhance’ the system. Eliminate those as a cause by starting up in safe mode, holding ß when you hear the startup sound and releasing it when you see the Apple logo. Safe mode disables third-party extensions, so if the issue crops up in it, you can be fairly confident they aren’t to blame.
You may also get a clue as to the cause by opening Console when your Mac has just restarted after one of these incidents. Search back in its logs to reach the last message containing BOOT_TIME, which marks the restart event, then look in the entries before that line for error messages and crashes.
Even experts can find it very hard to work out what caused a kernel panic. The good news is that macOS Sierra is far more robust than El Capitan. If your apps and peripherals are compatible with Sierra, upgrading to it should banish these kernel panics for good.
Log entries in the few seconds immediately before a forced shutdown or restart can give valuable clues as to its cause.