Chris, Hi. I had the same problem. I deleted Firebug and the problem persisted. I read from another user that he needed to restart Firefox, that didn't work either. Some said try Safari, that didn't work either.
In the end it was a novice thing:
I have helpers to insert an icon, like edit_icon, which return a nice image tag for the edit icon, etc.
One of these helper methods was the delete_icon method, where I wrote like this:
def delete_icon(object=nil)
link_to image_tag('icons/delete.jpg', :width => 20, :border=>0), object, :confirm => 'Are you sure?', :method => :delete
end
It was a (good) attempt at DRY, but better it would have been had I just had def delete_icon(object), and not object=nil, because it makes it clearer when I call it that I must pass it the object to destroy. Calling the same method with the object to be deleted worked for me.
In short: double check your helper methods if you're trying to DRY.