Error at Login

When i try to login into my Openfire it shows me an Error,

HTTP ERROR: 500

Could not initialize class org.jivesoftware.openfire.session.ClientSession

RequestURI=/index.jsp

Caused by:

java.lang.NoClassDefFoundError: Could not initialize class org.jivesoftware.openfire.session.ClientSession at org.jivesoftware.openfire.admin.index_jsp._jspService(index_jsp.java:415) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:491) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1074) at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:11 8) at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1065) at org.jivesoftware.util.LocaleFilter.doFilter(LocaleFilter.java:65) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1065) at org.jivesoftware.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingF ilter.java:41) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1065) at org.jivesoftware.admin.PluginFilter.doFilter(PluginFilter.java:69) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1065) at org.jivesoftware.admin.AuthCheckFilter.doFilter(AuthCheckFilter.java:98) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.ja va:1065) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:185) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:689) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:391) at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollect ion.java:146) at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139) at org.mortbay.jetty.Server.handle(Server.java:285) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:457) at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.j ava:751) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:500) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:209) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:357) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:329) at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475)

Powered by Jetty://

This was working fine till last month, I worked on it… But now it shows me this error.

So I am not able to login into it . Can Anyone get me a solution for this.