Harmful script

Below is the content of the popup I am getting.  I keep clicking the 'Yes' button, but it keeps coming up every few minutes.  How can I get rid of this script?

Windows Internet Explorer
           Stop running this script?

        A script on this page is causing Internet Explorer to run slowly.     
        If it continues to run, your computer might become unresponsive.                                                                                    

                | Yes |                        |  No  |                                             

JoeReeves