This is a problem with IE11… Microsoft in their legendary wisdom have changed the User Agent information provided by IE11 (see http://www.nczonline.net/blog/2013/07/02/internet-explorer-11-dont-call-me-ie/ for more info) and consequently have broken quite a lot of web applications (including Alfresco Share). FYI…. IE11 is (at the time of writing) not a currently supported browser