memtest86+ no errors, then massive errors when I tried to end testing

11-year-old laptop
Intel Core i7-2760QM 2.4GHz, 2nd-gen Sandy Bridge
RAM: 16 GB DDR3-1333
Motherboard: Dell 0YR8NN, Intel HM67 Express Chipset Family
memtest86+ 5.31b

Hello:

I ran memtest86+ 5.31b on 16 GB RAM in 11-year-old laptop.
I've used memtest86+ many times, but today something occurred that I've never seen before.

memtest86+ in SMP Mode (uses all cores, sometimes in parallel) completed 9 passes showing 0 errors. (First photo below.)

I pressed Esc to end test.
Instantly it showed red errors and the error count incremented rapidly, showing over 950,000 errors. (2nd photo below.)
I pressed C to open configuration panel, I selected Error Report Mode: default is Individual Errors, I selected Error Summary. (3rd photo below.)
memtest86+ seemed hung, as testing indicators were static and Time was not incrementing. except that the red plus sign in Memtest86+ logo kept flashing on and off.
Pressing keys had no effect

So, 9 full passes with no errors. Then, trying to quit displayed massive errors but with testing stopped and memtest86+ unresponsive to keyboard.

I read that SMP mode can cause false positives, showing errors when there is no problem with the RAM.
Maybe what I saw was another bug with SMP mode?

Hi.

Could be be related to SMP - Symmetric Multiprocessing.

1) Why are you testing to begin with? Is there a suspected issue?
2) Your system does not use ECC memory (just a fact on this type of system.)
3) I would suggest doing a Sequential test with multiple passes.
4) Are the unit thermals beyond the stated range?
5) Have you tried the memory test built into Windows 10 to correlate data?

How to Test Your Computer’s RAM for Problems