Just in from Neowin: http://www.neowin.net/news/microsoft-has-finally-fixed-the-freezing-issue-in-the-windows-10-anniversary-update 

If after installing this update you still are having a problem, MS has recommended the following:

Option 1: If you have a second administrator account on the PC that you can sign into, please do so and install the latest Windows 10 update, released on August 31st, 2016. After installing the update, reboot the PC and you should be able sign in successfully on your other account.

Option 2: Use the “go back” feature to uninstall the Anniversary Update. Once removed, you can re-install using the Windows Update Assistant by going to the Windows 10 download page and clicking the Update Now button.

There are two methods to uninstall the Anniversary Update:

Method 1: Using the Recovery Console

1. Restart your PC. When you get to the sign-in screen, hold the Shift key down while you select Power > Restart.

2. After your PC restarts to the Choose an option screen, select Troubleshoot > Advanced Options > Go back to the previous build. If you don’t see this option, try Method 2.

Method 2: Using the Settings app from Safe Mode

1. Restart your PC. When you get to the sign-in screen, hold the Shift key down while you select Power > Restart.

2. After your PC restarts to the Choose an option screen, select Troubleshoot > Advanced options > Startup Settings > Restart.

3. After your PC restarts, you'll see a list of options. Select 4 or F4 to start your PC in Safe Mode.

4. Open the Settings app.

5. Select Update & security and then the Recovery tab.

Under “Go back to an earlier build”, click the Get started button and follow the instructions.

Option 3: If you are uncomfortable with either of the earlier options or if the “go back” feature is not available to you, please contact support and one of our support agents can assist you in applying the resolution.

Source:

http://www.neowin.net/news/microsoft-has-finally-fixed-the-freezing-issue-in-the-windows-10-anniversary-update