while building a project in Eclipse using amdroid I face the following error. plz help me
UNEXPECTED TOP-LEVEL EXCEPTION:
java.lang.IllegalArgumentException: already added: Lcom/android/commands/am/Am$1;
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.dex.file.ClassDefsSection.add(ClassDefsSection.java:123)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.dex.file.DexFile.add(DexFile.java:143)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processClass(Main.java:338)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processFileBytes(Main.java:315)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.access$100(Main.java:56)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:266)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:244)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:130)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:108)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processOne(Main.java:284)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processAllFiles(Main.java:220)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.run(Main.java:176)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at java.lang.reflect.Method.invoke(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.ide.eclipse.adt.internal.build.DexWrapper.run(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.ide.eclipse.adt.internal.build.BuildHelper.executeDx(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.ide.eclipse.adt.internal.build.builders.PostCompilerBuilder.build(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:627)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:170)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:201)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:253)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:256)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:218)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:360)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Project$1.run(Project.java:523)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1800)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1782)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Project.internalBuild(Project.java:502)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Project.build(Project.java:94)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.ui.actions.BuildAction.invokeOperation(BuildAction.java:221)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.ui.actions.WorkspaceAction.execute(WorkspaceAction.java:162)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.ui.actions.WorkspaceAction$2.runInWorkspace(WorkspaceAction.java:483)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
[2010-12-27 17:44:15 - fallwallpaper]: Dx1 error; aborting
[2010-12-27 17:44:15 - fallwallpaper] Conversion to Dalvik format failed with error 1
UNEXPECTED TOP-LEVEL EXCEPTION:
java.lang.IllegalArgumentException: already added: Lcom/android/commands/am/Am$1;
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.dex.file.ClassDefsSection.add(ClassDefsSection.java:123)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.dex.file.DexFile.add(DexFile.java:143)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processClass(Main.java:338)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processFileBytes(Main.java:315)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.access$100(Main.java:56)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:266)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:244)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:130)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:108)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processOne(Main.java:284)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.processAllFiles(Main.java:220)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.dx.command.dexer.Main.run(Main.java:176)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at java.lang.reflect.Method.invoke(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.ide.eclipse.adt.internal.build.DexWrapper.run(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.ide.eclipse.adt.internal.build.BuildHelper.executeDx(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at com.android.ide.eclipse.adt.internal.build.builders.PostCompilerBuilder.build(Unknown Source)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:627)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:170)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:201)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:253)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:256)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:218)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:360)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Project$1.run(Project.java:523)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1800)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1782)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Project.internalBuild(Project.java:502)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.Project.build(Project.java:94)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.ui.actions.BuildAction.invokeOperation(BuildAction.java:221)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.ui.actions.WorkspaceAction.execute(WorkspaceAction.java:162)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.ui.actions.WorkspaceAction$2.runInWorkspace(WorkspaceAction.java:483)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
[2010-12-27 17:44:15 - fallwallpaper]: Dx at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
[2010-12-27 17:44:15 - fallwallpaper]: Dx1 error; aborting
[2010-12-27 17:44:15 - fallwallpaper] Conversion to Dalvik format failed with error 1

I'm an end-user, trying to learn how to develop apps. I have some