Here's the log -- see the last line -- the mentioned line#22 is the  <Loader ... /> line in the context.xml.
Nov 16, 2010 10:16:38 PM org.apache.tomcat.util.digester.Digester startElement 
SEVERE: Begin event threw exception 
org.eclipse.virgo.kernel.osgi.framework.ExtendedClassNotFoundException: org.apache.catalina.loader.WebappLoader in KernelBundleClassLoader: [bundle=org.eclipse.gemini.web.tomcat_1.1.0.RELEASE] 
 at org.eclipse.virgo.kernel.userregion.internal.equinox.KernelBundleClassLoader.loadClass(KernelBundleClassLoader.java:139) 
 at java.lang.ClassLoader.loadClass(ClassLoader.java:248) 
 at org.apache.tomcat.util.digester.ObjectCreateRule.begin(ObjectCreateRule.java:205) 
 at org.apache.tomcat.util.digester.Rule.begin(Rule.java:153) 
 at org.apache.tomcat.util.digester.Digester.startElement(Digester.java:1356) 
 at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(AbstractSAXParser.java:501) 
 at com.sun.org.apache.xerces.internal.parsers.AbstractXMLDocumentParser.emptyElement(AbstractXMLDocumentParser.java:179) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanStartElement(XMLDocumentFragmentScannerImpl.java:1343) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2755) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:511) 
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:808) 
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) 
 at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:119) 
 at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205) 
 at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522) 
 at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1642) 
 at org.apache.catalina.startup.ContextConfig.processContextConfig(ContextConfig.java:799) 
 at org.apache.catalina.startup.ContextConfig.contextConfig(ContextConfig.java:742) 
 at org.apache.catalina.startup.ContextConfig.init(ContextConfig.java:1019) 
 at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:273) 
 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119) 
 at org.apache.catalina.core.StandardContext.init(StandardContext.java:5654) 
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4425) 
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791) 
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771) 
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:546) 
 at org.eclipse.gemini.web.tomcat.internal.TomcatServletContainer.startWebApplication(TomcatServletContainer.java:120) 
 at org.eclipse.gemini.web.internal.StandardWebApplication.start(StandardWebApplication.java:90) 
 
 at org.eclipse.virgo.web.core.internal.WebBundleLifecycleListener.onStarted(WebBundleLifecycleListener.java:120) 
 
 at org.eclipse.virgo.kernel.install.artifact.internal.ArtifactStateMonitor.onStarted(ArtifactStateMonitor.java:205) 
 at org.eclipse.virgo.kernel.install.artifact.internal.AbstractInstallArtifact.asyncStartSucceeded(AbstractInstallArtifact.java:273) 
 at org.eclipse.virgo.kernel.install.artifact.internal.AbstractInstallArtifact.access$0(AbstractInstallArtifact.java:270) 
 at org.eclipse.virgo.kernel.install.artifact.internal.AbstractInstallArtifact$StateMonitorSignal.signalSuccessfulCompletion(AbstractInstallArtifact.java:223) 
 at org.eclipse.virgo.kernel.core.internal.BundleStartTracker$1.run(BundleStartTracker.java:140) 
 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
 at java.lang.Thread.run(Thread.java:619) 
 
Caused by: java.lang.ClassNotFoundException: org.apache.catalina.loader.WebappLoader 
 at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:506) 
 at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:422) 
 at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:410) 
 at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107) 
 at org.eclipse.virgo.kernel.userregion.internal.equinox.KernelBundleClassLoader.loadClass(KernelBundleClassLoader.java:135) 
 ... 37 more 
Nov 16, 2010 10:16:38 PM org.apache.catalina.startup.ContextConfig processContextConfig 
SEVERE: Parse error in context.xml for /EMA-Server 
org.eclipse.virgo.kernel.osgi.framework.ExtendedClassNotFoundException: org.apache.catalina.loader.WebappLoader in KernelBundleClassLoader: [bundle=org.eclipse.gemini.web.tomcat_1.1.0.RELEASE] 
 at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:2806) 
 at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:2832) 
 at org.apache.tomcat.util.digester.Digester.startElement(Digester.java:1359) 
 at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(AbstractSAXParser.java:501) 
 at com.sun.org.apache.xerces.internal.parsers.AbstractXMLDocumentParser.emptyElement(AbstractXMLDocumentParser.java:179) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanStartElement(XMLDocumentFragmentScannerImpl.java:1343) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2755) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648) 
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:511) 
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:808) 
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) 
 at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:119) 
 at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205) 
 at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522) 
 at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1642) 
 at org.apache.catalina.startup.ContextConfig.processContextConfig(ContextConfig.java:799) 
 at org.apache.catalina.startup.ContextConfig.contextConfig(ContextConfig.java:742) 
 at org.apache.catalina.startup.ContextConfig.init(ContextConfig.java:1019) 
 at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:273) 
 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119) 
 at org.apache.catalina.core.StandardContext.init(StandardContext.java:5654) 
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4425) 
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791) 
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771) 
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:546) 
 at org.eclipse.gemini.web.tomcat.internal.TomcatServletContainer.startWebApplication(TomcatServletContainer.java:120) 
 at org.eclipse.gemini.web.internal.StandardWebApplication.start(StandardWebApplication.java:90) 
 
 at org.eclipse.virgo.web.core.internal.WebBundleLifecycleListener.onStarted(WebBundleLifecycleListener.java:120) 
 
 at org.eclipse.virgo.kernel.install.artifact.internal.ArtifactStateMonitor.onStarted(ArtifactStateMonitor.java:205) 
 at org.eclipse.virgo.kernel.install.artifact.internal.AbstractInstallArtifact.asyncStartSucceeded(AbstractInstallArtifact.java:273) 
 at org.eclipse.virgo.kernel.install.artifact.internal.AbstractInstallArtifact.access$0(AbstractInstallArtifact.java:270) 
 at org.eclipse.virgo.kernel.install.artifact.internal.AbstractInstallArtifact$StateMonitorSignal.signalSuccessfulCompletion(AbstractInstallArtifact.java:223) 
 at org.eclipse.virgo.kernel.core.internal.BundleStartTracker$1.run(BundleStartTracker.java:140) 
 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
 at java.lang.Thread.run(Thread.java:619) 
 
Caused by: org.eclipse.virgo.kernel.osgi.framework.ExtendedClassNotFoundException: org.apache.catalina.loader.WebappLoader in KernelBundleClassLoader: [bundle=org.eclipse.gemini.web.tomcat_1.1.0.RELEASE] 
 at org.eclipse.virgo.kernel.userregion.internal.equinox.KernelBundleClassLoader.loadClass(KernelBundleClassLoader.java:139) 
 at java.lang.ClassLoader.loadClass(ClassLoader.java:248) 
 at org.apache.tomcat.util.digester.ObjectCreateRule.begin(ObjectCreateRule.java:205) 
 at org.apache.tomcat.util.digester.Rule.begin(Rule.java:153) 
 at org.apache.tomcat.util.digester.Digester.startElement(Digester.java:1356) 
 ... 33 more 
Caused by: java.lang.ClassNotFoundException: org.apache.catalina.loader.WebappLoader 
 at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:506) 
 at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:422) 
 at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:410) 
 at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107) 
 at org.eclipse.virgo.kernel.userregion.internal.equinox.KernelBundleClassLoader.loadClass(KernelBundleClassLoader.java:135) 
 ... 37 more 
Nov 16, 2010 10:16:38 PM org.apache.catalina.startup.ContextConfig processContextConfig 
SEVERE: Occurred at line 22 column 58