After upgrading my BIOS the problem came back again with the 4.15 kernels. I was able to solve the issue by adding noapic to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default grub, e.g.:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash noapic"
Once I did that, the kernels worked fine as did intel-microcode.
I'll update the description and details of the ticket to reflect my findings.
After upgrading my BIOS the problem came back again with the 4.15 kernels. I was able to solve the issue by adding noapic to GRUB_CMDLINE_ LINUX_DEFAULT in /etc/default grub, e.g.:
GRUB_CMDLINE_ LINUX_DEFAULT= "quiet splash noapic"
Once I did that, the kernels worked fine as did intel-microcode.
I'll update the description and details of the ticket to reflect my findings.