It's just got weirder.
This morning it's not working on Chrome or IE, but has started working again on Firefox!
IE is just a blank page (though looking as the source it looks like the login page) the page name is higgen but the first part of the URL says j_security_check
Chrome is giving a 500
java.lang.NullPointerException org.apache.jsp.jsp.HomePage_jsp._jspService(HomePage_jsp.java:1953) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) com.adventnet.servicedesk.filter.EncodingFilter.doFilter(EncodingFilter.java:162) org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1069) org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcessor.java:274) org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:455) org.apache.struts.tiles.TilesRequestProcessor.processForwardConfig(TilesRequestProcessor.java:320) org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:279) org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482) org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507) javax.servlet.http.HttpServlet.service(HttpServlet.java:697) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) com.adventnet.servicedesk.filter.EncodingFilter.doFilter(EncodingFilter.java:162) org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:350) com.adventnet.servicedesk.authentication.NTLMV2CredentialAssociationFilter.doFilter(NTLMV2CredentialAssociationFilter.java:34) com.adventnet.servicedesk.authentication.NTLMV2Filter.doFilter(NTLMV2Filter.java:176) org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:75)