var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		aboutbtn_01_over = newImage("images/aboutbtn_01-over.gif");
		aboutbtn_01_down = newImage("images/aboutbtn_01-down.gif");
		contactbtn_01_over = newImage("images/contactbtn_01-over.gif");
		contactbtn_01_down = newImage("images/contactbtn_01-down.gif");
		ceinfobtn_01_over = newImage("images/ceinfobtn_01-over.gif");
		ceinfobtn_01_down = newImage("images/ceinfobtn_01-down.gif");
		coursebtn_01_over = newImage("images/coursebtn_01-over.gif");
		coursebtn_01_down = newImage("images/coursebtn_01-down.gif");
		homebtn_01_over = newImage("images/homebtn_01-over.gif");
		homebtn_01_down = newImage("images/homebtn_01-down.gif");
		preloadFlag = true;
	}
}