Unity web player not calling up webpages using JS in internet explorer

Hi I have an online version of my game online which opens external webpages at certain points throughout using

Application.ExternalEval("window.open('http://www.yourwebname.html','name')");

This works perfectly on firefox (PC & Mac) and Safari (Mac) but i get no response using Internet Explorer (PC)

Is there anything I can do to sort this?

Thanks