>Off the Beaten Path>Internet Explorer 11
RA is developed using IE because it actually makes development easier than FF or Chrome. I was on IE9 until a few weeks ago. I upgraded to IE10 for a few days and then figure that I should just get the latest and greatest so now I'm on IE11. Everything on RA should work out of the box, without any special configuration or installation.
The problem you're having is probably related to compatibility mode. I've experienced this myself and I don't know why it happens. In a nutshell, IE goes into compatibility mode by switching to use IE7's rendering engine. It also reports to RA that it's IE7 instead of its real version. RA doesn't really care about the browser version. The site should still work with IE7, except that IE7 looks really bad.
My current theory is that one of the ads is misbehaving and creates invalid HTML code. IE detects this and goes into compatibility mode. It seems like once IE goes into compatibility mode for one page, then all the pages for a site would be rendered in the same mode. This is only a theory because I'm not able to reproduce the problem ever since it happened.