Hi Adriano,
Thanks for looking, I still get the error message though: http://www.fr.midwalesdesign.com/wp-content/uploads/sidebar-search.jpg
I'm trying to add the sidebar search view to the Categories taxonomy archive, but it also pops up when I try and add it to any page or post. I can select the View as in your screengrab, but then when I do I get the error in my screengrab.
Thanks