Somethin's wrong in the neighbourhood!

Avatar Rick Churchill
Recently my "13inch early 2015 MacBook Pro" often restarts when left idle. Sometimes the mouse curser becomes "sticky" and video on Youtube will stutter as if the CPU is under too much load. As I write this I realise I should have looked at Activity Monitor to see if I can work out what is loading the CPU.

What should I look for and is there any other diagnostic apps I can try?

The report says "Fatal Error"

Re: Somethin's wrong in the neighbourhood!

Avatar Euan Williams
Was all well before this event - no hints or signs of impending breakdown?

Is your Drive too full? You should leave at least 12-15% free space to give macOS wriggle room - this is especially needed when dealing with large files such as images.

There's a wide choice, in no particular order, between
A. hardware electronic failure; B. app corruption; C. OS corruption; D. drive or RAM memory failure; E. cache corruption; F. font corruption to suggest just a few.

If the system is trying to access failing memory sectors that can produce hangs and failures. This could be poor RAM or drive, but failing RAM is very rare and yours is soldered so reseating it is not appropriate. If the drive is failing (they do) remember that SSDs (flash) tend to fail without warning - unlike traditional hard drives. Your SSD is replaceable, but that is a remote issue unless you want to increase drive capacity.

Think back about any recent App updates or installs which might cause conflicts.

1. Clear all caches and check for non-Apple app interference by doing a safe boot. Restart normally afterwards. If the problem persists try safe boot again and run for some time to see if the problem appears. If so, check for rogue non-Apple app, delete. Try normal again.

2. Start from a 'known-good' external drive to see if the problem disappears. Boot up will be slow and there may be a performance deficit, but not cursor hangs nor crashes.

3. Re-install macOS (remember to do a TimeMachine or clone backup first) and choose between:
Command (⌘)-R
Install the latest macOS that was installed on your Mac.

Upgrade to the latest macOS compatible with your Mac.

Install the macOS that came with your Mac, or the closest version still available.

4. Start while pressing 'D' to access the built-in Apple Hardware Test or Apple Diagnostics utility, depending on your Mac model. Or use Option-D to start up from this utility over the Internet.

Hope this helps a bit.

Re: Somethin's wrong in the neighbourhood!

Avatar Rick Churchill
Thank you Euan.

Since reducing the number of open tabs in Firefox, closing all apps, backing up then restarting, the MacBook has been behaving itself; the curser is fluid and the MacBook has not restarted when left idle. I have activity Monitor running so I am ready to pounce if there is any stickiness with the curser. I will then resort to your suggestions to see which may cure the situation.

I had 69 GBytes free (this should be sufficient although it is less than 7% of my 1 TByte SSD) and since taking on your suggestion of clearing all the caches, this has grown to 114 Gbytes

Re: Somethin's wrong in the neighbourhood!

Avatar Tony Still
To add to Euan's excellent list (though I wouldn't personally resort to reinstalling macOS too quickly), I always run Disk Utility's First Aid (was just verify) I. these circumstances. You really want it to come back clean but a successful "repair" by DU is reassuring too.

Since Firefox seems to be implicated, it would be worth looking for its CPU and RAM consumption next time you run it with many tabs open. If FF is forcing macOS into a lot of swapping (non-zero 'Swap Used' in the Memory tab) then your system will slow, even with SSD, just without that worrying click-click noise you get when thrashing a mechanical hard drive. High CPU usage speaks for itself; I have seen Safari threads running at 100% CPU when simply viewing some nasty, complex web pages: closing the page works well in that situation but I don't know how clear individual page CPU is when using FF.