Sick laughter from my Mac friends once again...
Can you believe it? Yet another Vista Update crash. What a joke that operating system is.

And can you believe how Vista is set up to install these updates automatically, and then turn off the computer automatically - WITHOUT WARNING - in the middle of anything you're doing, losing any unsaved data?! Unbelievable.

Here's what happened this time: an automatic update decided to happen, turned the computer off, and then got into an endless cycle of "Configuring updates 3 of 3, don't turn off your computer", then the computer shutting down, starting up and doing the same again.

Solution: use System Restore to go back to a previous working setup.

Turn the computer off during this cycle, by holding the power button down for a few seconds.

You now need to get into the "Vista Windows Recovery Environment" - sounds grim, eh?! There are two possible ways to get there:

1. On a factory-supplied computer, there may be a "System Repair" option on the F8 Boot-up screen:
Start the computer, and as it starts, press f8 repeatedly. You'll enter a startup menu. Choose 'repair my computer'
You'll then get a selection of things to do - choose the one about using System Restore. Then follow the instructions in the link below (from the appropriate place!)

2. Otherwise, start the computer with the Vista DVD in the CD drive.
Follow this great tutorial: http://www.bleepingcomputer.com/tutorials/tutorial142.html

Then: once back in windows (assuming the above works), find and start Windows Update in your start menu, choose 'Change Settings' and choose options that (a) let you decide what to install and when; (b) don't include the 'recommended' updates (tick box at the bottom).
You just cannot trust MS on these updates. Bad, isn't it?