Thanks a lot :-),

it was the Slim Stat Analytics Plugin by Jason Crouse :-(. Now with the deactivation of this plugin, everything with the flashing is okay and the search result page is shown properly.
I have another little problem with the search function. How can i get more detailed information about the search result on the search result page.
I mean two or more sentence under every Link on these page. At the moment the result is only a number with one word. I wish i could get more detailed information.
Thanks