Run-time Error '91' When Using .findnext

is it just me and my copy of Excel 2003 or does the following code taken directly out out Microsoft Visual Basic Help result in a run-time error, with the last "Loop While Not" line of code highlighted as the problem?

I was trying to get a multiple find working on my userform, and was always getting the error, so thought I'd try the code in it's most basic form, and I'm still getting the error?


With Worksheets(1).Range("a1:a500")
Set c = .find(2, LookIn:=xlValues)
If Not c Is Nothing Then
firstAddress = c.Address
Do
c.Value = 5
Set c = .FindNext(c)
Loop While Not c Is Nothing And c.Address firstAddress
End If
End With

I'm sure I must be just doing something stupid!

This code goes through the range A1:A500 and replaces any cells that contain the value 2 with the value 5.