UnauthorizedAccessException
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.BeginWriteCore(Byte[] bytes, Int32 offset, Int32 numBytes, AsyncCallback userCallback, Object stateObject)
   at System.IO.FileStream.FlushWrite(Boolean calledFromFinalizer)
   at System.IO.FileStream.Dispose(Boolean disposing)
   at Microsoft.Win32.WinInetCache.WriteStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at Microsoft.Win32.WinInetCache.WriteStream.CloseEx(CloseExState closeState)
   at System.Net.Cache.ForwardingReadStream.Dispose(Boolean disposing, CloseExState closeState)
   at System.IO.Stream.Close()
   at System.Windows.Media.Imaging.BitmapDownload.ReadCallback(IAsyncResult result)
   at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   at System.Net.Cache.ForwardingReadStream.ReadComplete(IAsyncResult transportResult)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()