I've used a simple macro in Excel 2003/Windwos XP SP3 to create two x-y
charts, one with three x-y pairs based on max. 6000 rows; here is the start:

Dim ws As Worksheet
Set ws = ActiveSheet
ws.Select
ws.Name = "Data"
Application.ScreenUpdating = False
Sheets("Data").Select
Range("B3").Select
Charts.Add
ActiveChart.ChartType = xlXYScatterLines
ActiveChart.SetSourceData Source:=Sheets("Data").Range("A1:X3"),
PlotBy:= _
xlRows
ActiveChart.SeriesCollection.NewSeries
ActiveChart.SeriesCollection(1).XValues = "=Data!R8C2:R6000C2"
ActiveChart.SeriesCollection(1).Values = "=Data!R8C9:R6000C9"
ActiveChart.SeriesCollection(1).Name = "=Data!R7C9"
ActiveChart.Location Whe=xlLocationAsNewSheet

Everything worked perfectly until recently (the charts would be created in
~1 sec) until Excel 2003 had to be reinstalled by IT due to a corrupted file.
Ever since, the macro started running exceedingly slow, up to 10 min, to
create two simple charts! Re-installation would not help, and the Core Due
processor show 60% load during that time. We can't find any way to fix it
(rewriting, reinstallation etc. would not help), but Fn-Break always shows
the program stopping at one of the ActiveChart.SeriesCollection(1).Values
lines of code...

Any idea what may be causing this behavior and how to fix it?