我按登陆的SERVLET帮其他页面写了SERVLET，结果一进带有FORM ACTION=下面第二和第三个SERVLET的页面就一直报错500，大家帮忙看看是什么问题吧，想了好半天了想不通啊。估计是很简单的问题。
web.xml:
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>CheckUsersServlet</servlet-name>
<servlet-class>checkUsers.CheckUsersServlet</servlet-class>
</servlet>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>coursebasicinfo</servlet-name>
<servlet-class>servlet.coursebasicinfo</servlet-class>
</servlet>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>Userinfo</servlet-name>
<servlet-class>servlet.Userinfo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CheckUsersServlet</servlet-name>
<url-pattern>/CheckUsersServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>coursebasicinfo</servlet-name>
<url-pattern>/coursebasicinfo</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Userinfo</servlet-name>
<url-pattern>/Userinfo</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list></web-app>


HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exceptionorg.apache.jasper.JasperException: /userinfomanagement.jsp(147,6) Invalid standard action
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:88)
org.apache.jasper.compiler.Parser.parseStandardAction(Parser.java:1156)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1448)
org.apache.jasper.compiler.Parser.parse(Parser.java:133)
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:216)
org.apache.jasper.compiler.ParserController.parse(ParserController.java:103)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:167)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:306)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:273)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:566)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.Apache Tomcat/6.0.13

应该是你的servlet的java代码出了问题，比如死循环啊什么的。