10.04.3 -> 12.04 install hangs, grub won't boot. memtest86+ culprit

[rob]

During the 10.04.03 -> 12.04 upgrade, the install hung.

I logged in and checked the process tree for the precise installer, and saw that the memtest86+.post process was defunct and unresponsive to all kill signals. I had to kill the frontend process to continue the install.

pstree -p 8126
precise(8126)─┬─precise(9103)───dpkg(20835)───frontend(22585)─┬─memtest86+.post(22599)
              │ ├─{frontend}(22592)
              │ └─{frontend}(22594)
              ├─sh(14888)───sleep(23516)
              ├─{precise}(8386)
              ├─{precise}(8387)
              └─{precise}(14907)

 ps -ef|grep 22599
root 22599 22585 0 00:22 pts/3 00:00:00 [memtest86+.post] <defunct>

grub produced an error, but I couldn't re-run grub from the command line while the install was running since it claimed that grub was not installed.

After the install completed, grub would not boot and dropped into the grub recover console. I had to boot up the live CD in recover mode and issue a "grub-install /dev/sda" to get the system to recover.

Once it booted, the same defunct memcheck86+.post process occurred every time I attempted to rebuild grub. Removing the memcheck86+ package (apt-get remove memcheck86+) let grub finish and now the system boots again without a problem.