Minecraft Launcher will not update/launch on Mac

I opened the existing Launcher and was informed there was a new version of the Launcher available. I clicked the link and the Launcher quit, but now will not update and will not load

What I expected to happen was...:{*}{*}

For the new version of the Launcher to install and work properly

What actually happened was...:

When opening the Launcher a dialog box stating "Updating Minecraft..." appears very briefly (<0.5sec) and then disappears from the screen. At times it appears that the "Cancel" button is being hilited/clicked, but I may be mistaken.

I have tried restarting the machine, ensuring that Java is up to date, deleting and reinstalling Minecraft. I have moved the "minecraft" folder out of Application Support, and when I open the Launcher again, it recreates the "minecraft" folder with

• an empty "launcher" folder

• two text files:

  • launcher_log.txt

  • nativeUpdaterLog.txt

... before quitting. I've attached these files.

Steps to Reproduce:
Download the latest Minecraft installer from the site (I'm assuming, onto a Mac with the specified configuration, OS, and Java version) and try to launch it.