Unable to boot normally. Will boot to Safe Mode or Recovery Disk.

Those elements appear to only be in my ~/Library because I can't find them anywhere in /System or /Library. I assumed that "user" elements wouldn't be a factor because I never get to log in?

At this point erasing the entire drive isn't an option because I don't have anywhere to make a 1TB backup, but I will try making a fresh user account and seeing if there is any change.

SMART Report:

smartctl 6.5 2016-05-07 r4318 [Darwin 16.7.0 x86_64] (local build)

Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===

Model Family: Hitachi Deskstar E7K1000

Device Model: Hitachi HDE721010SLA330

Serial Number: STN608MS1VDVJK

LU WWN Device Id: 5 000cca 35eda1969

Firmware Version: ST0KA36E

User Capacity: 1,000,204,886,016 bytes [1.00 TB]

Sector Size: 512 bytes logical/physical

Rotation Rate: 7200 rpm

Device is: In smartctl database [for details use: -P show]

ATA Version is: ATA8-ACS T13/1699-D revision 4

SATA Version is: SATA 2.6, 3.0 Gb/s

Local Time is: Sat Aug 5 09:03:05 2017 EDT

SMART support is: Available - device has SMART capability.

SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===

SMART overall-health self-assessment test result: PASSED

General SMART Values:

Offline data collection status: (0x84) Offline data collection activity

was suspended by an interrupting command from host.

Auto Offline Data Collection: Enabled.

Self-test execution status: ( 0) The previous self-test routine completed

without error or no self-test has ever

been run.

Total time to complete Offline

data collection: (14090) seconds.

Offline data collection

capabilities: (0x5b) SMART execute Offline immediate.

Auto Offline data collection on/off support.

Suspend Offline collection upon new

command.

Offline surface scan supported.

Self-test supported.

No Conveyance Self-test supported.

Selective Self-test supported.

SMART capabilities: (0x0003) Saves SMART data before entering

power-saving mode.

Supports SMART auto save timer.

Error logging capability: (0x01) Error logging supported.

General Purpose Logging supported.

Short self-test routine

recommended polling time: ( 1) minutes.

Extended self-test routine

recommended polling time: ( 235) minutes.

SCT capabilities: (0x003d) SCT Status supported.

SCT Error Recovery Control supported.

SCT Feature Control supported.

SCT Data Table supported.

SMART Attributes Data Structure revision number: 16

Vendor Specific SMART Attributes with Thresholds:

ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE

1 Raw_Read_Error_Rate 0x000b 100 100 016 Pre-fail Always - 0

2 Throughput_Performance 0x0005 100 100 054 Pre-fail Offline - 28

3 Spin_Up_Time 0x0007 126 126 024 Pre-fail Always - 455 (Average 455)

4 Start_Stop_Count 0x0012 100 100 000 Old_age Always - 1506

5 Reallocated_Sector_Ct 0x0033 100 100 005 Pre-fail Always - 0

7 Seek_Error_Rate 0x000b 100 100 067 Pre-fail Always - 0

8 Seek_Time_Performance 0x0005 125 125 020 Pre-fail Offline - 33

9 Power_On_Hours 0x0012 092 092 000 Old_age Always - 61569

10 Spin_Retry_Count 0x0013 100 100 060 Pre-fail Always - 0

12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 1074

192 Power-Off_Retract_Count 0x0032 099 099 000 Old_age Always - 1726

193 Load_Cycle_Count 0x0012 099 099 000 Old_age Always - 1726

194 Temperature_Celsius 0x0002 117 117 000 Old_age Always - 51 (Min/Max 12/65)

196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 0

197 Current_Pending_Sector 0x0022 100 100 000 Old_age Always - 0

198 Offline_Uncorrectable 0x0008 100 100 000 Old_age Offline - 0

199 UDMA_CRC_Error_Count 0x000a 200 200 000 Old_age Always - 0

SMART Error Log Version: 1

No Errors Logged

SMART Self-test log structure revision number 1

No self-tests have been logged. [To run self-tests, use: smartctl -t]

SMART Selective self-test log data structure revision number 1

SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS

1 0 0 Not_testing

2 0 0 Not_testing

3 0 0 Not_testing

4 0 0 Not_testing

5 0 0 Not_testing

Selective self-test flags (0x0):

After scanning selected spans, do NOT read-scan remainder of disk.

If Selective self-test is pending on power-up, resume after 0 minute delay.

Nothing in this computer has been replaced. Ever. It came with the Hitachi drive. I do remember that (when my optical drive would work) I ran either the Apple diagnostics or Techtool (though I vaguely remember it was text-based, ala Terminal) that my drive was in danger and should be repaired. That was easily over 4 years ago.

I'll download and try Rember tonight. I should point out that when this issue originally occurred, I only had the 2 2GB chips that originally came with the computer installed. I had purchased 2 4GB chips some time ago but had never gotten around to installing them. When I saw the [failed] com.apple.ucupdate issue I went looking and people mentioned that the cause for system launch [fail]ures was potentially due to a lack of memory so I decided now was the time to install the other chips. (Hey, now I can run Elder Scrolls reliably...well, except for the lack of graphic acceleration.) The system seems quite happy with them. I thought the first 2 would be in the same Bank, so these two would be in the same Bank, but looking at the EtreCheck report it seems they had one each in Bank 0 and Bank 1. If it seriously will make a difference I can do a RAM chip square dance, but I'd prefer to concentrate on it booting first.

USB Devices - I have a Logitech Marble Mouse. (Not the one they currently show on their website.) There have been times when, in the past, the system did not like to boot if the mouse was plugged in initially, though unplugging it and then plugging it back in seemed to pacify the system. In the interest of taking no chances I ran the Uninstall for the Logitech Control Center (though it still shows in the "Software Installs" portion of the report) and have made sure the mouse was unplugged during any bootup procedures until Apple kindly asks me to return it. (It works fine without the driver, I just can't use the special buttons.) At the moment I don't have easy access to any other mice, except for a 2nd Marble Mouse, but I can try switching them. (My teenager's been using it for months, though, so I may need to give it a bath first.)

Thank you all for your responses. I sincerely appreciate it. One small update before I begin acting on these - after digging a bit into "why can't I run Apple Hardware Test" I found a link to where I could download the test (from Apple). I then booted to the Recovery disk and turned off SIP so I could move it into /System/Library/CoreServices. I tried booting, but the system absolutely did NOT seem to like booting with the SIP off. Not into normal or Safe Mode. I was able to get it to boot back to the Recovery Disk. I went ahead and manually moved the files through the Terminal (which I should have done originally but just didn't think of it) and restored SIP. I then ran Disk Utility just to be sure, and told it to reinstall the OS a third time...just to be sure. I came across three differences I hadn't seen before:

1) When I booted to Recovery, it asked me what language I wanted (it asked me something else first but I don't remember). Booting into the Recovery Disk hasn't done that before. At least not recently. It might have once, years ago? Anyway, this was different.

2) When I left the computer to try to boot overnight it got to almost the 3/4ths point of the progress bar, but when I woke up I wasn't hearing any disk activity so I did a hard-shutdown.

(Despite installing the .diagnostics folder, I still do not seem to be able to boot to Apple Hardware Test.)

3) When I booted into Safe Mode, it went through the opening screens (Setting Up Your Mac, do you want us to send reports to Apple) as if I'd just updated from a previous OS version. I don't recall it doing these the last two times I reinstalled the OS.

I don't know if any of these are of any consequence, but anything about the OS that seems different, at this point, I'm trying to make a note of. I'll create a new user and see if that makes a difference, remove the User Launch Agents and Internet Plugs from my personal account, and download Rember to run tonight.

Let me elaborate on my "pruning" of the system. I went into several folders removing any files that were older than 2015, minus anything starting com.apple. These included:

/System/Library/Extensions,

/System/Library/LaunchAgents (left org.openbsd.ssh-agent.plist),

/System/Library/LaunchDaemons,

/System/Library/PreferencePanes,

/System/Library/StartupItems (removed everything).

I also went into /Library and looked for similar items. I also investigated any /Internet Plug-Ins folders I found, and also the /Library/Widgets folder. This was prior to my 2nd reinstallation of the OS which I did to make sure I hadn't removed anything vital.

This was prompted primarily by this article: https://eclecticlight.co/2016/09/20/my-mac-only-runs-properly-in-safe-mode/

After running Etrecheck, I specifically sought out and eliminated third-party software I had found. Flash, Boom2, the Logitech Control Center, Virtualbox, ActiveGS, and probably others I'm forgetting.

Rember got through three loops through the night, though it's entirely possible the computer went to sleep at some point? Regardless, there were no errors during those three loops.

On a more dire note, during another attempt to boot normally my computer went grey longer than usual (at the halfway point), then came back with a checkerboard of graphical artifacts covering the entire screen. I wish I could get the Hardware Test to run. If the Graphics card is going out, at this point it'll cost half as much as a new system to repair this one.

I was able to get Apple Hardware Test installed on a USB drive and boot from it. It provided me two codes:

4MOT/4/40000003: HDD-1282 (after a quick test)

4MOT/4/40000003: HDD-1299 (after a 3 hour Extended test)

Both of these seem to point to my hard drive motor and/or the temperature of the sensor at the hard drive.

I do know that the back central fan stopped working about 3 years ago. (Didn't realize there was a vent back there, what with the stand in the way.) I had an extension at the time that would provide me fan speeds and system temperatures and I was able to monitor the system's internal temperatures. Since that time, I've never brought the screen above 50% Brightness because that seemed to cause a lot of heat. Every once in a while the CD Drive fan will crank up to 5400RPM and stay that way until I literally shut the computer down. (I used to be able to restart, but with the energy management additions of one of the recent OS releases, I now have to shut all the way down.) With careful management, I've never felt it get "hot" (and certainly not up to the 160 degrees that caused screen artifacts to appear before I realized what was going on).

I'm probably gonna take it in a local shop (nearest Apple Store is 2 hours away) and see if a general look-over, undusting, and perhaps replacing one or more fans helps any, but I'm concerned that:

a) I don't believe that a fan-not-working would cause the hang that I'm having, and

b) There were NO other codes given by the Apple Hardware Test.

Does anyone know of any utilities that work under Sierra that would provide me the output of the temperature gauges throughout the computer, and does anyone know of any utilities that would specifically test my graphics card? (I'd like to think the AHT did, but...)

I thought I had done this before, but whether I hadn't, or if I had and something is different now, deleting all of the .ktext files starting AMD and ATI has allowed the computer to reboot outside of safe mode. On the plus side, I have sound again (finally). However, there is still a lot of graphic artifact from effectively not using the graphics card. (Any sort of video is unwatchable due to constant screen refreshing, Safari since High Sierra has entire sections of web pages blacked out.) I'm going to do a bit more digging and see if perhaps it can use one of the other files be used besides the 4670 and perhaps operate under a lesser feature set, or if replacing with something else would work. If you or anyone else has more information here, I'd certainly appreciate it.

Turning off all extensions as you suggested had no effect.