Java EE (Java Enterprise Edition) General Discussion

I have a HelloWorld servlet. Real simple. Packaged as a war. Works perfectly on one box running Linux FC5/Tomcat 5.5.17.

But on this box, running FC5/Tomcat 5.5.23, I can't even deploy it! Here's the output from $CATALINA_HOME/logs/catalina.out when I run ant install:

Jun 14, 2007 10:55:44 PM org.apache.catalina.startup.HostConfig deployWAR
INFO: Deploying web application archive hello-world.war
Jun 14, 2007 10:55:44 PM org.apache.commons.modeler.Registry registerComponent
SEVERE: Null component Catalina:type=JspMonitor,name=jsp,WebModule=//localhost/hello-world,J2EEApplication=none,J2EEServer=none

Any clues? When I try running the servlet with http://localhost:8080/hello-world/HelloWorld I get HTTP/500 with the following stack trace:

javax.servlet.ServletException: Error allocating a servlet instance
	org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
	org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
	org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:870)
	org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
	org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
	org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
	org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:685)
	java.lang.Thread.run(Thread.java:619)

root cause

java.lang.NoClassDefFoundError: javax/servlet/http/HttpServlet
	java.lang.ClassLoader.defineClass1(Native Method)
	java.lang.ClassLoader.defineClass(ClassLoader.java:620)
	java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
	org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1847)
	org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:873)
	org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1326)
	org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1205)
	org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
	org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
	org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:870)
	org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
	org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
	org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
	org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:685)
	java.lang.Thread.run(Thread.java:619)