Hi Neil

Just a quick reply as finishing off some other work.

A few things I would run to test it.
(sometimes I find Apple RAM test not all that helpful, whereas the following is 
very good).
Just be aware it can take a really really long time to test it all, as it does 
a huge amount of tests to all the modules. (I’ve seen some take hours to 
complete - 
Rember - http://www.kelleycomputing.net/rember/

I’d also run the hard drives just to rule them out. For a good program I use 
Smart Disk Utility from here - 
(the demo is fine for a one off test).
https://www.volitans-software.com/apps/smart-utility/

Could also be something “heating up” perhaps? So it runs for a while, until a 
part is heated up a bit more. (unlikely, but worth a check anyway).
For older iMac’s that have had hard drives replaced this is a good program to 
help control the Fans a bit more then the Apple one - 
http://www.hddfancontrol.com

But I’d be checking the RAM first would be my start.

Hope something there helps. If I think of more, I’ll post back as well.
Kind regards
Daniel

---
Daniel Kerr
MacWizardry

Phone: 0414 795 960
Email: <daniel AT macwizardry.com.au>
Web:   <http://www.macwizardry.com.au>


**For everything Apple**

NOTE: Any information provided in this email may be my personal opinion and as 
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> On 13 Mar 2019, at 8:52 pm, Neil Houghton <n...@possumology.com> wrote:
> 
> Hi Ronni,
>  
> The problem is that all RAM modules show as OK both in System report and 
> Etrecheck (which says the performance is Excellent) and it seems that the 
> iMac thinks I have a fully functioning 24GB.
>  
> It is obviously something that only shows up in the more heavy duty checks 
> that AHT uses.
>  
> The problem is that the error message does not seem to indicate which module 
> is problematic - so I guess it is trial and error and repeated use of AHT?
>  
> Thanks
>  
>  
> Neil
>  
> From: <wamug.org.au-wamug-boun...@lists.wamug.org.au> on behalf of Ronni 
> Brown <ro...@mac.com>
> Reply-To: <wamug@wamug.org.au>
> Date: Wednesday, 13 March 2019 at 17:52
> To: <wamug@wamug.org.au>
> Subject: Re: Strange iMac freezes
>  
> Hi Neil,
>  
> Yes that AHT does indicate Bad Ram. On your menu bar go to: Apple > About 
> This Mac > click on System Report... > then click on Memory in the Hardware 
> section.
> 
> 
> There you should be able to see which 0xb740bf98  module has failed and which 
> slot it is installed in.
> 
> Kind Regards,
> Ronni
>  
>  Ronni Brown’s iPad Pro 12.9-inch 256GB 
>  
> 
> On 13 Mar 2019, at 5:18 pm, Neil Houghton <n...@possumology.com> wrote:
> 
>> 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: <wamug.org.au-wamug-boun...@lists.wamug.org.au> on behalf of Neil 
>> Houghton <n...@possumology.com>
>> Reply-To: "wamug@wamug.org.au" <wamug@wamug.org.au>
>> Date: Tuesday, 12 March 2019 at 17:20
>> To: "wamug@wamug.org.au" <wamug@wamug.org.au>
>> 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: <wamug.org.au-wamug-boun...@lists.wamug.org.au> on behalf of Neil 
>> Houghton <n...@possumology.com>
>> Reply-To: "wamug@wamug.org.au" <wamug@wamug.org.au>
>> Date: Tuesday, 12 March 2019 at 16:02
>> To: "wamug@wamug.org.au" <wamug@wamug.org.au>
>> 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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