I have installed Tomcat on windows XP through the Tomcat installer. I have installed JDK 1.6. But when I start Tomacat from services.msi on XP, I get the following error: java.lang.ClassNotFoundException: org.apache.catalina.core.AprLifecycleListener at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at sun.misc.Launcher$ExtClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at org.apache.commons.digester.ObjectCreateRule.begin(ObjectCreateRule.java:204) at org.apache.commons.digester.Rule.begin(Rule.java:152) at org.apache.commons.digester.Digester.startElement(Digester.java:1286) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanStartElement(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)