I'm getting intermittent "Runtime error '16': Expression too complex"
using the following code. It seems like if I step it through slowly,
it'll work for a while. What's wrong? I'm using Excel 11.8033.8036
with VBA 6.4.9972 if that matters, on Server 2003.

Option Explicit
Option Base 1

Private Function Sum(Arr() As Long) As Long
Sum = 0
If (Not Arr) < -1 Then
Dim i As Long
For i = LBound(Arr) To UBound(Arr)
Sum = Sum + Arr(i)
Next i
End If
End Function

Private Function Count(Arr() As Long) As Long
Count = UBound(Arr) - LBound(Arr) + 1
End Function

Private Function Average(Arr() As Long) As Double
Average = Sum(Arr) / Count(Arr)
End Function

Public Sub Test()
Dim x(1 To 30) As Long
Dim i As Long
For i = LBound(x) To UBound(x)
Randomize
x(i) = CInt(30 * Rnd) + 1
Next i
Debug.Print Average(x)
End Sub