Comment 12 for bug 1305165

May be a long shot, but this stack trace looks very similar to the inner exception part of the one reported in Bug 1300942:

Error: System.InvalidOperationException: Failed to compare two elements in the array. ---> System.ArithmeticException: Function does not accept floating point Not-a-Number values.
   at System.Math.Sign(Single value)
   at ORTS.Viewer3D.RenderItem.Comparer.Compare(RenderItem x, RenderItem y)
   at System.Collections.Generic.ArraySortHelper`1.QuickSort(T[] keys, Int32 left, Int32 right, IComparer`1 comparer)
   at System.Collections.Generic.ArraySortHelper`1.Sort(T[] keys, Int32 index, Int32 length, IComparer`1 comparer)
   --- End of inner exception stack trace ---
   at System.Collections.Generic.ArraySortHelper`1.Sort(T[] keys, Int32 index, Int32 length, IComparer`1 comparer)
   at System.Array.Sort[T](T[] array, Int32 index, Int32 length, IComparer`1 comparer)
   at System.Collections.Generic.List`1.Sort(Int32 index, Int32 count, IComparer`1 comparer)
   at System.Collections.Generic.List`1.Sort(IComparer`1 comparer)
   at ORTS.Viewer3D.RenderFrame.Sort()
   at ORTS.Processes.UpdaterProcess.Update()
   at ORTS.Processes.UpdaterProcess.DoUpdate()
   at ORTS.Processes.UpdaterProcess.UpdaterThread()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
for which we may have a fix,

Chris