Aptana 3 is not starting and only says "An error has occurred. See the log file." - aptana3

Question

I have checked the log file and see the following: (an ideas how to resolve?)
!ENTRY org.eclipse.osgi 4 0 2012-10-22 09:44:40.920
!MESSAGE Application error
!STACK 1
java.lang.NoClassDefFoundError: org/eclipse/core/resources/IContainer
at com.aptana.rcp.IDEApplication.start(IDEApplication.java:125)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
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:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
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.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
Caused by: org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter$TerminatingClassNotFoundException: An error occurred while automatically activating bundle org.eclipse.core.resources (427).
at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:463)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:400)
at org.eclipse.osgi.internal.loader.SingleSourcePackage.loadClass(SingleSourcePackage.java:35)
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:473)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:429)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:417)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 13 more
Caused by: org.osgi.framework.BundleException: Exception in org.eclipse.core.resources.ResourcesPlugin.start() of bundle org.eclipse.core.resources.
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:734)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:683)
at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:299)
at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:440)
at org.eclipse.osgi.internal.loader.BundleLoader.setLazyTrigger(BundleLoader.java:268)
at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
... 22 more
Caused by: org.eclipse.core.internal.dtree.ObjectNotFoundException: Tree element '/dlpage-css/database/setup/countries.txt' not found.
at org.eclipse.core.internal.dtree.AbstractDataTree.handleNotFound(AbstractDataTree.java:257)
at org.eclipse.core.internal.dtree.DeltaDataTree.getData(DeltaDataTree.java:585)
at org.eclipse.core.internal.dtree.DataDeltaNode.asBackwardDelta(DataDeltaNode.java:50)
at org.eclipse.core.internal.dtree.NoDataDeltaNode.asBackwardDelta(NoDataDeltaNode.java:59)
at org.eclipse.core.internal.dtree.NoDataDeltaNode.asBackwardDelta(NoDataDeltaNode.java:59)
at org.eclipse.core.internal.dtree.NoDataDeltaNode.asBackwardDelta(NoDataDeltaNode.java:59)
at org.eclipse.core.internal.dtree.DataDeltaNode.asBackwardDelta(DataDeltaNode.java:47)
at org.eclipse.core.internal.dtree.DeltaDataTree.asBackwardDelta(DeltaDataTree.java:88)
at org.eclipse.core.internal.dtree.DeltaDataTree.reroot(DeltaDataTree.java:816)
at org.eclipse.core.internal.dtree.DeltaDataTree.reroot(DeltaDataTree.java:815)
at org.eclipse.core.internal.dtree.DeltaDataTree.reroot(DeltaDataTree.java:815)
at org.eclipse.core.internal.dtree.DeltaDataTree.reroot(DeltaDataTree.java:792)
at org.eclipse.core.internal.watson.ElementTree.immutable(ElementTree.java:518)
at org.eclipse.core.internal.resources.SaveManager.restore(SaveManager.java:710)
at org.eclipse.core.internal.resources.SaveManager.startup(SaveManager.java:1528)
at org.eclipse.core.internal.resources.Workspace.startup(Workspace.java:2503)
at org.eclipse.core.internal.resources.Workspace.open(Workspace.java:2251)
at org.eclipse.core.resources.ResourcesPlugin.start(ResourcesPlugin.java:439)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:711)
at java.security.AccessController.doPrivileged(Native Method)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:702)
... 28 more

Answer 1

This just happened to me again and at the worst time possible.
I really didn't want to have to rebuild the whole workspace but I found this answer and it worked!
For anyone interested, I had the exact same problem and deleting the
file .metadata/.plugins/org.eclipse.core.resources/.snap did the trick
for me.
This file is located in your broken workspace's folder.
From: http://www.eclipse.org/forums/index.php/mv/msg/156204/734920/#msg_734920

Answer 2

Try deleting/renaming the Workspace folder (eg. Documents\Aptana 3 Studio Workspace), that worked for me

Answer 3

I increased the -Xms and -Xmx values in STS.ini and it solved the problem.
New Values:
-Xms256m
-Xmx2048m