First some explanation about the problem.
The situation is when you have a Joomla 1.5 site with sh404sef 2.1.4 component and you want to add additional section for a blog for example and you want to use K2 2.4 for this.
So in this case you have additional menu item called for example ‘blog’ where you see a blog of your K2 articles. But you also want to have the tags and the search.
The problem is that when you hit on a tag you go to the page with the tags but you don’t see the other modules for the ‘blog’ item (you are redirected to a page without Itemid).
The same is with the search results page.
And one additional fix for a prefix in the url for your K2 blog.