Crash during downloads

[mastersign]

Both BenchDashboard.exe and bench.exe crash during download of app resources (16 queued). bench.exe shows the following stacktrace:

Unbehandelte Ausnahme:Unbehandelte Ausnahme: Unbehandelte Ausnahme:  Unbehandelte Ausnahme: System.IndexOutOfRangeException: Der Index war außerhalb des Arraybereichs.
   bei System.Collections.Generic.List`1.Add(T item)
   bei Mastersign.Bench.BenchTasks.<>c__DisplayClass44_0.<RunTasks>b__0(TaskInfo info)
   bei Mastersign.Bench.BenchTasks.<>c__DisplayClass55_0.<DownloadAppResources>b__0(Object o, DownloadEventArgs e)
   bei Mastersign.Bench.Downloader.OnDownloadStarted(DownloadTask task)
   bei Mastersign.Bench.Downloader.Worker(Int32 no)
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   bei System.Threading.ThreadHelper.ThreadStart()System.IndexOutOfRangeException: Der Index war außerhalb des Arraybereichs.
   bei System.Collections.Generic.List`1.Add(T item)
   bei Mastersign.Bench.BenchTasks.<>c__DisplayClass44_0.<RunTasks>b__0(TaskInfo info)
   bei Mastersign.Bench.BenchTasks.<>c__DisplayClass55_0.<DownloadAppResources>b__1(Object o, DownloadEventArgs e)
   bei Mastersign.Bench.Downloader.OnDownloadEnded(DownloadTask task)
   bei Mastersign.Bench.Downloader.<>c__DisplayClass49_0.<Worker>b__1(Object o, AsyncCompletedEventArgs e)
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   bei System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
   bei System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)

[mastersign]

This could be a race condition on List.Add()