I Had an issue in IE7, IE8, IE9, IE10 when I click on the calendar icon the calendar does not appear. I then scrolled to the top of the page and there it was.
So the issue in Joomla to view the pop-up calendar when you click on the icon is to edit media/system/js/calendar.js file
Replace:
if(Calendar.is_ie){br.y+=document.body.scrollTop;br.x+=document.body.scrollLeft;}else{br.y+=window.scrollY;br.x+=window.scrollX;}
with:
if(Calendar.is_ie){br.y+=document.body.document.documentElement.scrollTop;br.x+=document.body.document.documentElement.scrollLeft;}
Now my calendar icon links work in IE7, IE8, IE9 and IE10