I got the following stacktrace after clicking "New Server" icon (see screenshot)

java.lang.NoClassDefFoundError: org/eclipse/wst/server/ui/internal/wizard/ClosableWizardDialog
at org.jboss.tools.jst.web.ui.action.server.SelectServerActionDelegate.newServer(SelectServerActionDelegate.java:132)
at org.jboss.tools.jst.web.ui.action.server.SelectServerActionDelegate.access$1(SelectServerActionDelegate.java:130)
at org.jboss.tools.jst.web.ui.action.server.SelectServerActionDelegate$3.widgetSelected(SelectServerActionDelegate.java:120)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:228)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3823)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3422)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2382)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2346)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2198)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:493)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:488)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:382)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)
at org.eclipse.equinox.launcher.Main.run(Main.java:1236)

Environment
eclipse.buildId=I20080617-2000
Windows XP
jdk1.5.0_15
org.jboss.ide.eclipse.archives.core (2.1.1.GA) "JBossTools Archives Core Plugin" [Active]
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org.jboss.ide.eclipse.as.classpath.ui (1.1.2.GA) "JBoss AS Classpath Ui Plug-in" [Starting]
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org.jboss.ide.eclipse.as.ui (1.1.2.GA) "JBoss AS Ui Plug-in" [Active]
org.jboss.ide.eclipse.as.ui.mbeans (1.1.2.GA) "Mbeans Plug-in" [Active]
org.jboss.ide.eclipse.core (2.1.1.GA) "JBoss Core Plug-in" [Active]
org.jboss.ide.eclipse.firstrun (2.1.1.GA) "JBossIDE First Run Plug-in" [Active]
org.jboss.ide.eclipse.freemarker (1.0.1.GA) "FreeMarker IDE" [Starting]
org.jboss.ide.eclipse.help (2.1.1.GA) "JBossIDE for Eclipse Help Plug-in" [Starting]
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org.jboss.ide.eclipse.jdt.j2ee.core (2.1.1.GA) "JBoss Development J2EE Core Plug-in" [Starting]
org.jboss.ide.eclipse.jdt.j2ee.ui (2.1.1.GA) "JBoss Development J2EE UI Plug-in" [Starting]
org.jboss.ide.eclipse.jdt.j2ee.xml.ui (2.1.1.GA) "JBoss Development J2EE XML UI Plug-in" [Starting]
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org.jboss.ide.eclipse.ui (2.1.1.GA) "JBoss UI Plug-in" [Starting]
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org.jboss.tools.common.projecttemplates (2.1.1.GA) "JBoss Tools Project Templates" [Active]
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org.jboss.tools.common.verification (2.1.1.GA) "org.jboss.tools.common.verification" [Active]
org.jboss.tools.common.verification.ui (2.1.1.GA) "JBoss Tools Verification Framework" [Active]
org.jboss.tools.esb.core (1.0.0.GA) "pluginName" [Active]
org.jboss.tools.esb.ui (1.0.0.GA) "ESB XML" [Starting]
org.jboss.tools.hibernate.ui.veditor (3.2.3.GA) "Visual Editor Plugin" [Starting]
org.jboss.tools.hibernate.ui.view (3.2.3.GA) "View Plug-in" [Starting]
org.jboss.tools.hibernate.xml (2.1.1.GA) "Hibernate 3.0 XML" [Active]
org.jboss.tools.hibernate.xml.ui (2.1.1.GA) "Hibernate 3.0 XML UI" [Starting]
org.jboss.tools.jsf (2.1.1.GA) "JBoss Tools JSF" [Active]
org.jboss.tools.jsf.text.ext (2.1.1.GA) "Jsf Text Editors Extensions" [Active]
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org.jboss.tools.jsf.ui (2.1.1.GA) "JBoss Tools JSF UI" [Active]
org.jboss.tools.jsf.verification (2.1.1.GA) "JSF Verification" [Active]
org.jboss.tools.jsf.vpe.adf (2.1.1.GA) "ADF support for JBoss Visual Page Editor Plug-in" [Resolved]
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org.jboss.tools.jsf.vpe.facelets (2.1.1.GA) "Facelets Plug-in" [Active]
org.jboss.tools.jsf.vpe.jsf (2.1.1.GA) "JSF support for JBoss Visual Page Editor Plug-in" [Active]
org.jboss.tools.jsf.vpe.myfaces (2.1.1.GA) "MyFaces support for JBoss Visual Page Editor Plug-in" [Active]
org.jboss.tools.jsf.vpe.richfaces (2.1.1.GA) "Richfaces VPE Support Plug-in" [Active]
org.jboss.tools.jsf.vpe.seam (2.1.1.GA) "Seam VPE support Plug-in" [Active]
org.jboss.tools.jsf.vpe.tomahawk (2.1.1.GA) "Tomahawk VPE Support Plug-in" [Active]
org.jboss.tools.jst.firstrun (2.1.1.GA) "JBoss AS Initialization Plug-in" [Active]
org.jboss.tools.jst.jsp (2.1.1.GA) "Jsp Editor Plug-in" [Active]
org.jboss.tools.jst.server.jetty (2.1.1.GA) "Jetty Generic Server Definition Plug-in" [Starting]
org.jboss.tools.jst.server.jrun (2.1.1.GA) "JRun Generic Server Definition Plug-in" [Starting]
org.jboss.tools.jst.server.resin (2.1.1.GA) "Resin Generic Server Definition Plug-in" [Starting]
org.jboss.tools.jst.web (2.1.1.GA) "Web" [Active]
org.jboss.tools.jst.web.debug (2.1.1.GA) "Web Debug" [Starting]
org.jboss.tools.jst.web.debug.ui (2.1.1.GA) "Web Debug UI" [Starting]
org.jboss.tools.jst.web.tiles (2.1.1.GA) "Web Tiles" [Active]
org.jboss.tools.jst.web.tiles.ui (2.1.1.GA) "JBoss Tools Tiles" [Starting]
org.jboss.tools.jst.web.ui (2.1.1.GA) "Web UI" [Active]
org.jboss.tools.jst.web.verification (2.1.1.GA) "WEB Verification" [Active]
org.jboss.tools.seam.core (2.1.2.GA) "Seam Core Plug-in" [Active]
org.jboss.tools.seam.text.ext (2.1.2.GA) "Seam Text Editors Extensions" [Active]
org.jboss.tools.seam.ui (2.1.2.GA) "Seam GUI Tools" [Active]
org.jboss.tools.seam.xml (2.1.2.GA) "JBoss Tools Seam XML" [Active]
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org.jboss.tools.struts (2.0.0) "org.jboss.tools.struts" [Active]
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org.jboss.tools.struts.text.ext (2.1.0.GA) "Struts Text Editors Extensions" [Starting]
org.jboss.tools.struts.ui (2.1.0.GA) "JBoss Tools Struts UI" [Active]
org.jboss.tools.struts.validator.ui (2.1.0.GA) "JBoss Tools Struts Validator" [Starting]
org.jboss.tools.struts.verification (2.1.0.GA) "Struts Verification" [Active]
org.jboss.tools.struts.vpe.struts (2.1.0.GA) "Struts support for JBoss Visual Page Editor Plug-in" [Resolved]
org.jboss.tools.vpe (2.1.1.GA) "Visual Page Editor" [Active]
org.jboss.tools.vpe.html (2.1.1.GA) "HTML support for JBoss Visual Page Editor Plug-in" [Active]
org.jboss.tools.vpe.jsp (2.1.1.GA) "JSP support for JBoss Visual Page Editor Plug-in" [Starting]
org.jboss.tools.vpe.ui.palette (2.1.0.GA) "JBoss Tools Palette" [Starting]
org.jboss.tools.vpe.ui.palette (2.1.1.GA) "JBoss Tools Palette" [Starting]
org.jboss.tools.vpe.xulrunner (2.1.1.GA) "Browser (XULRunner) Plug-in" [Active]