While running Ubuntu 18.04.1 on a laptop, the following errors were observed.
mce: hardware error cpu 0 machine check 0 bank 6 ae0000000040110a
mce: hardware error tsc 0 addr ffb07540 misc 238a0000086
mce: hardware error processor 0:40651 time 1540082330 socket 0 Apic 0 microcode 24
ipmi dmi invalid offset 0
The system would stop in the single user mode.
2.1 Running fsck
There were some problems with a hard disk partition and it was rectified by running the fsck
command for that disk partition, accepting all the corrections suggested by fsck
$ fsck /dev/sda6
2.2 Re-install of Ubuntu 18.04.1
Ubuntu 18.04.01 was reinstalled. The disk was partitioned such that the OS was on a separate (root) partition and the user home directories were on another partition. The OS was reinstalled on the disk partition mounted as / and care was taken such that the disk partition containing the user directories was not formatted during the re-install process. To do this, one has to choose
as the installation type and NOT check the format box for the partitions containing the user home directories.
2.3 Post re-install
After, the re-installation, there were no errors.