Had the same problem.
Unfortunately, I got the instructions on how to go about it is not so readily understood.
Now that I have played me for hours with the problem I want to pose the same problem this in some detail for all other:
Problem:
Device: Samsung Galaxy S2
After updating to Jelly Bean 4.1.2 I have the widget installed SKalender.
Then, the phone could not be served. TouchWiz kept crashing after a few seconds and it appeared the error message:
> Start TouchWiz stopped <
Thus, it was not possible to remove the widget still arrive in the settings. Not even further witchen one side longer possible.
Also, no menu or whatever.
Solution:
It can be done:
The error message with O.K. confirm and pull the Notifications panel (top bar) down.
Top left is the button for settings (cogs)
This tap, scroll down and start the task manager.
You will see a list of "Installed Apps"
This list left witchen until the last top-item "All"
There scroll down to SKalender and remove it. (Tapping, then appears a selection)
Behold - the phone goes again!
Whether it's better now, to delete or remove the SKalender the TouchWiz, I do not know. It would be nice if they would here to have your say specialists. With me went back after the SKalender was gone.