I just upgraded my Vodafone Samsung Galaxy SII to the latest Jelly Bean 4.1.2, (Had to do it OTA as Kies does not work with Windows 8).
Everything was fine until it started repeatedly crashing.
I was playing around setting up all my widgets and application access and I dragged the full page calendar widget onto a page and the system slowed and then entered into a crashing loop where I would get a “TouchWiz Home has Crashed message” or similar, I would click “OK” and approx 20 seconds later it would crash again.
The Work Around
Be patient but you should be able to get to your phones settings page.(click Ok on the error, swipe down the “Action Bar?” (the one at the top) and click on the “Settings” icon, top right).
Once the settings page has opened, the crash will stop occurring. So now we need to fix it?
Go to “Application Manager > All” scroll to the bottom and you will find “TouchWiz Home”.
Click on it, choose “Force Stop” and “Clear Data”.
Now clearing the data will mean you loose all your widget’y / app’y setup that you have been slugging away at, but you will now be able to return to your TouchWiz Home without a crash occurring.
Now you have to start again and setup your shortcuts and widgets, doh!.
For now just don’t use the full page calendar widget, until vodafone tells you otherwise.