When the page is scrolled down so that the RadTagCloud is partially visible and the control gets the focus, under Chrome its first item will be focused and the page will be scrolled to the top.
The issue is not reproducible with Q1 2015 SP1 and Chrome 43
The issue is related to way TadTagCloud items are focused in Chrome. The following override could be used as temporary workaround: <script type="text/javascript"> Telerik.Web.UI.RadTagCloud.prototype._enableKeyboardNavigation = function(){}; </script>