Comment # 3 on bug 1208571 from Stefan Hundhammer

What happened here would be pure speculation at this point. I guess we'll have
to wait for a retry with a future 15.5 snapshot. Setting to "NEEDINFO" in the
meantime.

You could try running "memtest86" to check if your PC developed a hardware
defect, or a smartmontools self-test from one of the working installations.