GPO affects Address bar in IE Browser

I have implemented GPO in my environment. To visit a website we used to normally type in the website address in the format http://www.website.com, but now it would only work if you wipe clean the address bar and type in www.websit.com (without the http://). An error message pops up saying “Address Bar “Access to the resource http://www.website.com’ has been disallowed”” Then you click ok to close the pop up. What setting in GPO controls this as I have removed all the restriction I put on internet explorer but still can’t get around this problem.