I've read the release notes. I did specify when asked that grub should be set up on SDA, the same place that it was originally set up. This is my second installation and update this weekend, with the same result. The first time, I simply rebooted and reinstalled LMDE. This time, I just walked away from the machine, and I'm posing on another computer. It should be noted that as upgrade progresses, bits and pieces of the system become unresponsive. For instance, I'm unable to restart my browser, to post on this forum from that machine.
Tail of the installation log looks about like this:
setting up grub-pc common 1.99-22.1
installing new version of config file /etc/bash_completion.d/grub
installing new version of config file /etc/grub.d/20_linux_xen
installing new version of config file /etc/grub.d/10_linux
installing new version of config file /etc/grub.d/30_os-prober
installing new version of config file /etc/grub.d/00_header
setting up grub2-common 1.99-22.1
setting up grub-pc-bin 1.99-22.1
setting up grub-pc 1.99-22.1
I have slow DSL, and it takes more than an hour to download all the updates, so I just hate to try again. The computer sits there with the cursor blinking below "setting up grub-pc", waiting for me to do something about it.
I can't remember precisely which installation media I'm using - I believe it's from April of 2012. I used the same installation media to install onto the computer I'm posting from. This machine upgraded to UP4 without issues.
I'm looking forward to the release of an updated installation ISO - download once, use forever!!