perfromance center installation error

dear all
i have downloaded performance center 11 and I am trying to install it. in the configuration process I get an error as below:

[4/11/2011 4:39:41 PM]: [ERROR]: The "IIS6DeleteVirtualDirTask" task failed unexpectedly.
System.Runtime.InteropServices.COMException (0x80070003): The system cannot find the path specified.

at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)
at System.DirectoryServices.DirectoryEntry.Bind()
at System.DirectoryServices.DirectoryEntry.get_IsContainer()
at System.DirectoryServices.DirectoryEntries.ChildEnumerator..ctor(DirectoryEntry container)
at System.DirectoryServices.DirectoryEntries.GetEnumerator()
at HP.MSBuild.Extensions.Utils.IISUtils.isVirtualDirectoryExist(DirectoryEntry root)
at HP.MSBuild.Extensions.Utils.IISUtils.removeVirtualIfExist(DirectoryEntry root)
at HP.MSBuild.Extensions.Utils.IISUtils.RemoveVirtuaDir()
at HP.MSBuild.Extensions.Tasks.IIS6DeleteVirtualDirTask.Execute()
at Microsoft.Build.BuildEngine.TaskEngine.ExecuteInstantiatedTask(EngineProxy engineProxy, ItemBucket bucket, TaskExecutionMode howToExecuteTask, ITask task, Boolean& taskResult)

can anyone guide me?
thank you