Not blue but BLACK screen of death!

Hi ,
Over the years my PC has suffered slow startups, but I have been able to overcome them by finding the offending program that was hogging the startup and uninstalling it.
So this time, when my PC groaned and started slowly, I checked the startup, but nothing seemed amiss. Consequently I suspected a virus or some other bug had defeated Windows Defender. So I downloaded Malwarebytes and ran both programs a couple of times. No viruses, but about 4 PUPS.
Then something strange happened.
Instead of a slow startup when I turned on my PC, there is the usual peep to indicate that the PC is OK, but then the screen hangs on the "Starting Windows" window and a small red light comes on at the front of the PC (under the small green light below the on/off button).
I've looked in Device Manager : - no yellow warning signs.
So I uninstalled Malwarebytes, using Revo Uninstaller and the computer started up normally, for a day. Now it has returned to its hanging trick.
The only other thing that has changed, is that I have now loosened my control over allowing Microsoft to download Updates. (Since Win 10 came out I've used a program to prevent Microsoft from downloading Win 10 secretly, but thought I was safe now and uninstalled the program.)
Ever since that time (a month ago) I've received updates very regularly, which have been successfully downloaded. Before that the updates were unsuccessful.
My system :-AMD Athlon 2 quad cores, 8GB RAM, AMD Radeon HD 6570 graphics card, Samsung 850 EVO C: drive and WD 10 E: drive.
OS is Win 7 64 bit Service Pack 1 , which I bought as a genuine Microsoft set of discs, from a reputable source. (PC World/Currys)
Has anyone had the same problem?
I thought I would change the Startup options, so I ran msconfig and changed the option to "only load essential programs"
When I restarted the PC all I got after "Starting Windows" was the BLACK s.o.d.
Guess what? When I tried to start the PC in Safe Mode, by repeatedly pressing the F8 button BEFORE the "Starting Windows" appeared, all I got was BSOD, not blue, but BLACK.
I never thought that, at 78, I would lose the will to live, but I am determined that , with your help, this problem can be overcome. Either that or I'll have to go my bedroom, open the window and throw the blooming computer out, on to the patio!
Can anyone help? John
PS. Apologies to all concerned. As a novice computer operator, I placed my Post in the wrong section, believing that my title would explain my problem.
Would a Moderator please transfer my Post to a more appropriate Forum for me? Thanks, John