function RandomizeGenercImage()
{
    var randomnumber = Math.round((Math.random()*5));
    var imageArray = new Array();
    imageArray[0] = "/SiteResources/images/HeaderV1.jpg";
    imageArray[1] = "/SiteResources/images/HeaderV2.jpg";
    imageArray[2] = "/SiteResources/images/HeaderV3.jpg";
    imageArray[3] = "/SiteResources/images/HeaderV4.jpg";
    imageArray[4] = "/SiteResources/images/HeaderV5.jpg";
    imageArray[5] = "/SiteResources/images/HeaderV6.jpg";

    if(document.getElementById("HeaderImage")){
        document.getElementById("HeaderImage").src = imageArray[randomnumber];
    }    
}

addLoadEvent(RandomizeGenercImage);