另人恼怒的编译问题！请指教．

另人恼怒的编译问题！请jsp的高手指教．以前没有问题的．忽然老出现这样的问题是什么原因呢？我的路径的配置应该是没有问题的．谢谢

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

root cause

java.lang.NullPointerException
	org.apache.jsp.checklogin_jsp._jspService(checklogin_jsp.java:66)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

note The full stack trace of the root cause is available in the Apache Tomcat/5.0.30 logs.