Have used one click child plugin quite a few times before and it is great.
However now it seems to be breaking any new sites I am using it on. First thought it may be the host that didn't like it so tried it on another and it does the same.
Give the success message saying "null theme switched" and then as soon as you try and move to another area of the site, the whole thing goes down. The only solution to getting the site back (minus one click child theme plugin) I have found is to completely erase the installation and databases and start again.
Is this purely and issue with 3.4.1?