Are you getting errors trying to open .cfm and .cfc files like the following:

java.lang.ClassNotFoundException: org.cfeclipse.cfml.editors.CFMLEditor

Looking for a solution I came across many recommendations to update JVM to 1.5 or greater. Which I did, up to 1.6x now, which did not solve the delima. Honestly I think there is a version conflict with the Eclipse included with Flex Builder and the latest CFEclipse available. Have the CFEclipse developers not tested their latest release with Flex Builder?

My solution was to simply use an older version of CFEclipse, version 1.3.1.3. None of the versions above this would work. I'm so happy now to have CFEclipse capability.

To use an earlier version CFEclipse, be sure to uncheck "Show the latest version of a feature only" when installing the update and then select version 1.3.1.3 or earlier. Do not select the "Extras" available either.

My guess would be the class is failing to load because of some other missing class.
If you could post the full stack track of the error, that would be good.

I get the same error:

java.lang.ClassNotFoundException: org.cfeclipse.cfml.editors.CFMLEditor
   at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:405)
   at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:350)
   at org.eclipse.osgi.framework.adaptor.core.AbstractClassLoader.loadClass(AbstractClassLoader.java:78)
   at java.lang.ClassLoader.loadClass(Unknown Source)
   at org.eclipse.osgi.framework.internal.core.BundleLoader.loadClass(BundleLoader.java:275)
   at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:227)
   at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1248)
   at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:152)
   at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:142)
   at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:129)
   at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:48)
   at org.eclipse.ui.internal.WorkbenchPlugin$1.run(WorkbenchPlugin.java:240)
   at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:69)
   at org.eclipse.ui.internal.WorkbenchPlugin.createExtension(WorkbenchPlugin.java:236)
   at org.eclipse.ui.internal.registry.EditorDescriptor.createEditor(EditorDescriptor.java:252)
   at org.eclipse.ui.internal.EditorManager.createPart(EditorManager.java:842)
   at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:562)
   at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:384)
   at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:552)
   at org.eclipse.ui.internal.PartPane.setVisible(PartPane.java:283)
   at org.eclipse.ui.internal.presentations.PresentablePart.setVisible(PresentablePart.java:126)
   at org.eclipse.ui.internal.presentations.util.PresentablePartFolder.select(PresentablePartFolder.java:269)
   at org.eclipse.ui.internal.presentations.util.LeftToRightTabOrder.select(LeftToRightTabOrder.java:65)
   at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation.selectPart(TabbedStackPresentation.java:391)
   at org.eclipse.ui.internal.PartStack.refreshPresentationSelection(PartStack.java:1102)
   at org.eclipse.ui.internal.PartStack.setSelection(PartStack.java:1051)
   at org.eclipse.ui.internal.PartStack.showPart(PartStack.java:1256)
   at org.eclipse.ui.internal.PartStack.add(PartStack.java:442)
   at org.eclipse.ui.internal.EditorStack.add(EditorStack.java:109)
   at org.eclipse.ui.internal.EditorSashContainer.addEditor(EditorSashContainer.java:60)
   at org.eclipse.ui.internal.EditorAreaHelper.addToLayout(EditorAreaHelper.java:212)
   at org.eclipse.ui.internal.EditorAreaHelper.addEditor(EditorAreaHelper.java:202)
   at org.eclipse.ui.internal.EditorManager.createEditorTab(EditorManager.java:758)
   at org.eclipse.ui.internal.EditorManager.openEditorFromDescriptor(EditorManager.java:665)
   at org.eclipse.ui.internal.EditorManager.openEditor(EditorManager.java:628)
   at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2360)
   at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2295)
   at org.eclipse.ui.internal.WorkbenchPage.access$9(WorkbenchPage.java:2287)
   at org.eclipse.ui.internal.WorkbenchPage$9.run(WorkbenchPage.java:2273)
   at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:69)
   at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2268)
   at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2249)
   at org.eclipse.ui.ide.IDE.openEditor(IDE.java:371)
   at org.eclipse.ui.ide.IDE.openEditor(IDE.java:334)
   at org.eclipse.ui.actions.OpenFileAction.openFile(OpenFileAction.java:98)
   at org.eclipse.ui.actions.OpenSystemEditorAction.run(OpenSystemEditorAction.java:98)
   at org.eclipse.ui.views.navigator.OpenActionGroup.runDefaultAction(OpenActionGroup.java:120)
   at org.eclipse.ui.views.navigator.MainActionGroup.runDefaultAction(MainActionGroup.java:326)
   at org.eclipse.ui.views.navigator.ResourceNavigator.handleOpen(ResourceNavigator.java:650)
   at org.eclipse.ui.views.navigator.ResourceNavigator$6.open(ResourceNavigator.java:409)
   at org.eclipse.jface.viewers.StructuredViewer$2.run(StructuredViewer.java:741)
   at org.eclipse.core.internal.runtime.InternalPlatform.run(InternalPlatform.java:1044)
   at org.eclipse.core.runtime.Platform.run(Platform.java:783)
   at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:44)
   at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:148)
   at org.eclipse.jface.viewers.StructuredViewer.fireOpen(StructuredViewer.java:739)
   at org.eclipse.jface.viewers.StructuredViewer.handleOpen(StructuredViewer.java:968)
   at org.eclipse.jface.viewers.StructuredViewer$6.handleOpen(StructuredViewer.java:1067)
   at org.eclipse.jface.util.OpenStrategy.fireOpenEvent(OpenStrategy.java:243)
   at org.eclipse.jface.util.OpenStrategy.access$2(OpenStrategy.java:238)
   at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:277)
   at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
   at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:843)
   at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3125)
   at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2758)
   at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:1699)
   at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1663)
   at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:367)
   at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:143)
   at com.adobe.flexbuilder.standalone.FlexBuilderApplication.run(FlexBuilderApplication.java:103)
   at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:226)
   at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:376)
   at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:163)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
   at java.lang.reflect.Method.invoke(Unknown Source)
   at org.eclipse.core.launcher.Main.invokeFramework(Main.java:334)
   at org.eclipse.core.launcher.Main.basicRun(Main.java:278)
   at org.eclipse.core.launcher.Main.run(Main.java:973)
   at org.eclipse.core.launcher.Main.main(Main.java:948)