OK - prior to running the combo update I thought I’d run a couple more tests:

 

1)  I ran the Apple Hardware Test (AHT) in extended mode and it did report a 
problem (on pass 1):

4MEM/9/4000000 0xb740bf98

which I understand indicates a RAM problem.

 

2)  I then ran Etrecheck which reported no problem except

Last shutdown cause - 128- unknown

However the time of this shutdown would match me hitting the shutdown button in 
Apple Hardware test - so not really a problem.

 

So, my current thinking is:
AHT is finding a RAM problem
The RAM passes the normal bootup RAM check
Etrecheck shows all RAM modules check out OK
The problem could be a (few) bad sector(s) on one RAM module
Everything works fine until something tries to access the bad RAM sector(s)
 

I guess I now need to isolate the bad RAM module. Given I have 24GB RAM in 4 
modules then, assuming there is just one problem module, the iMac should 
continue to work fine on either 20GB or 16GB (depending on the size of the 
faulty RAM) while I get the bad RAM replaced.

 

I may or may not need to run the combo update - depending on whether the 
various hard shutdowns have caused any corruptions problems.

 

I will keep you informed on progress.

 

Cheers

 

 

Neil

 

From: <[email protected]> on behalf of Neil 
Houghton <[email protected]>
Reply-To: "[email protected]" <[email protected]>
Date: Tuesday, 12 March 2019 at 17:20
To: "[email protected]" <[email protected]>
Subject: Re: Strange iMac freezes

 

OK - further update - another freeze:

 

This time only MS Outlook was running and I was previewing attachments to an 
email (using the Outlook preview all button when the spinning beachball 
appeared.

At first I could see both Outlook and Finder using the command-tab switcher and 
checking the fast user switching drop-down menu worked OK - showing my user 
account logged in.

 

Then more strangeness happened:
All my desktop items “disappeared” though the desktop picture was still visible 
(if this had happened at the last freeze when using Firefox I would not have 
noticed since the desktop was obscured by the 2 Firefox windows)
Command-tab now only showed Outlook and NOT Finder - as if Finder had somehow 
quit and not relaunched.
I normally have the dock hidden but the cursor revealed it normally - showing 
no dot under the finder to show it was running.
I clicked the finder icon in the dock (hoping to relaunch finder) and the 
desktop picture immediately disappeared leaving a black background.
 

Currently:
Desktop is black but menubar and Outlook window are still showing.
Mousing over the hidden dock no longer reveals it.
The cursor shows the spinning beachball over the outlook window and menu items
The Outlook window can be moved but not resized
The cursor currently show the normal pointer over the right-hand Apple menu 
icons and the 1Password menu icon
The cursor shows the spinning beachball over the Onedrive and Dropbox menu icons
When the cursor is moused over the Malwarebytes menu icon it says “Background 
service is offline”
When the cursor is moved over the black desktop, it does not change state - ie 
it stays as ether the normal pointer or as the beachball depending what the 
state was just prior to moving onto the “black”
 

Continuing:
With the cursor over the Spotlight icon, it changed to the beachball and then 
the icon disappeared.
Picking on an Apple menu icon to click - this time the wireless status icon - 
resulted in the cursor now showing the spinning ball over all the Apple menu 
icons
Clicking on the 1Password and Malwarebytes menu icons also resulted in the 
cursor changing to showing the spinning ball over these menu icons
This time the other Apple menu icons did not actually disappear from the menu 
bar.
 

The problem has now occurred both with Outlook only running and with Firefox 
only running and It now seems to me that the problem is not with either app but 
with some basic OSX functionality at the finder/dock level (or the processes 
running these functions).

 

I think Ronni’s suggestion for the combo update is my best bet at this point.

 

I will report back with my progress - or lack thereof  ;o)

 

 

Cheers

 

 

Neil

 

 

 

 

From: <[email protected]> on behalf of Neil 
Houghton <[email protected]>
Reply-To: "[email protected]" <[email protected]>
Date: Tuesday, 12 March 2019 at 16:02
To: "[email protected]" <[email protected]>
Subject: Strange iMac freezes

 

Writing this from the laptop as my iMac has started playing up with strange 
‘freezes’ the likes of which I’ve never seen before – and I’ve had my share of 
crashes, freezes & hangs over the years!!

 

First my setup/hardware – which has been “enhanced” since purchase:
27” iMac 2.8GHz i7 - late 2009 - running OSX 10.11.6
24GB RAM - 2x8GB + 2x4GB
Internal Drive 1 - Mercury Electra 250GB SSD - boot drive containing OSX, 
applications and a bare “admin” user account
Internal Drive 2 - 3TB Toshiba partitioned as:
·         1.5TB volume - containing main user folder plus other data folders

·         1.0TB volume - currently empty (earmarked for media files)

·         500GB volume - containing my previous SL boot volume

 

This has all been working fine since the rebuild to replace the HDs and boost 
the RAM.

 

I have been out of town for a couple of weeks but shut down the compute and UPS 
and removed the plugs from the wall - so no chance of “power glitches” while we 
were away.

 

On return everything fired up OK (from memory) but pretty soon I had a freeze - 
I don’t remember the exact sequence but, pretty soon I ended up with just a 
black screen with a cursor. The cursor continued to respond to the mouse but I 
could not “wake up” anything else. Command option escape would not open a force 
quit window and I had no means of knowing if any apps were still running. All I 
could do was power down using the power button on the back of the iMac.

 

All  booted up OK but fairly soon I ran into problems - again I don’t remember 
the exact sequence but I do remember the desktop going black whilst some open 
window remained visible but soon I was back at the black screen & cursor. 
Again, all I could do was power down using the power button on the back of the 
iMac. At this point, I was worried that I might have some drive problem so I 
rebooted from my backup clone and used disk utility to run first aid on all 
drives/partitions. I ran top level on both internal drives and then volume 
level on all four volumes - in all cases the repair went fine with no issues 
noted.

 

Back to booting normally and again all seemed fine - for awhile - until another 
freeze - I just remember I was using Outlook this time.

 

Sometime (I don’t remember when) during all this I remember Acrobat reader 
opening - unprompted - a couple of times. The first time barely registered - I 
just quit it - the second time made me think “why did it do that?” I was also 
trying to research OSX black screen problems - I found plenty of references to 
this problem but generally associated with incomplete system updates and none 
with similar circumstances to mine. One common thread on a numbers of these 
threads seemed to be down to some login problem which made me go the user 
preference pane where I noticed two new Adobe items in the login items list - 
which, I guess could explain the unexpected opening of Adobe reader. I have now 
removed the Adobe items from the login items list but my freeze problems 
persist and so this was probably non-related.

 

 

The latest freeze is now ongoing – around 1 hour and I know that only a 
switch-off at the power button will get me out of it.
In this case the only app open was Firefox with two multi-tab windows on screen 
and one multi-tab window minimised in the dock. It froze with the spinning 
beach ball cursor – which still tracks the mouse movements.
Command-tab would not cycle me back to Finder.
Option-Command-Escape would not bring up the force-quit menu.
Mousing the cursor over the menu bar showed the spinning ball over all the 
Firefox menu items but the normal pointer over the right-hand Apple & 3rd party 
menu items.
I have the “fast user switching” menu item on so I clicked my user name to open 
the drop-down switching menu (I wanted to check if this looked “normal”) 
however, at that point most of the Apple menu items disappeared from the 
menu-bar. The Spotlight icon was still showing but clicking that turned the 
pointer to the beachball and, after a moment, the Spotlight icon also 
disappeared.
At present, both Firefox windows are still showing and I can switch between 
windows by clicking each window – but not between tabs within the window.
The menu bar still shows the left-hand Apple icon but the beachball cursor when 
over it. The full Firefox menu also shows – but again with the beachball.
The Dropbox, 1Password, Malwarebytes and Onedrive menu icons are still showing 
– but now with the beachball (although originally the shoed the normal pointer 
cursor).
Screen sleep initiated normally and the screen awoke from sleep normally with a 
keyboard input.
UPDATE:  I have just shut down using the power button and rebooted and quit the 
only reopened app (Firefox) and, for the moment, all looks fine. For the 
moment, I will leave it running while I have lunch and see if runs into any 
problems just sitting quietly doing nothing (from a user perspective!)

 

UPDATE:  Well, it has been running fine for a couple of hours now (but doing 
nothing) including screen sleep and rewake and system sleep and rewake/login - 
so I guess I will go back to using it and see if I can find any sort off 
pattern to the problem.

 

Any thoughts/ideas/suggestions gratefully received.

 

 

Cheers

 

 

Neil

 

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