current = 0;

function switchHeader(index) {
	$(".main_nav_block .top_menu li").removeClass("active").eq( index ).addClass("active");
	$(".main_nav_block .switch").hide().eq( index ).css({display: 'block'});
}

function rotateHeader(){
	current++;
	if (current >= $(".main_nav_block .top_menu li").length) {
		current = 0;
	}	
	switchHeader(current);
}

$(function(){

	timeout = 3000;

	timer = setInterval(rotateHeader, timeout);

	$(".main_nav_block .top_menu li").hover(function(){
		current = $(".main_nav_block .top_menu li").index(this);
		switchHeader(current);
		clearInterval(timer);
	}, function(){
		timer = setInterval(rotateHeader, timeout);
	});
	
	$(".main_nav_block .switch").hover(function(){
		clearInterval(timer);
	}, function(){
		timer = setInterval(rotateHeader, timeout);
	});

});