Unity Launcher and Menu Bar Missing

While it appears to be an issue that has plagued a hand-full of Ubuntu users, for at least 6 years, it still seems difficult to find a fix.
On installing Nvidia drivers in Ubuntu, after logging in, the entire Unity and menu bar are nowhere to be seen.

Rather than being presented with the usual desktop interface.

The user has displayed for them the lovely purple Ubuntu background instead (in whatever incarnation that version is using).

Luckily there's a fix...

Cinnamon Shutdown Button Missing

First step when I install Ubuntu is to replace the Unity desktop with Cinnamon from Linux Mint. The problem is for a long time I was pressing the shutdown button and being presented with a dialog that only gave me the option to shutdown and not to cancel.

If I'm guessing what was going on correctly this is because Ubuntu uses "logind" and Cinnamon uses "consolekit", which means there are two solutions.