Excel CSV Error
 

From our intranet we routinely expose a link to export underlying datasets
to excel via
Response.ContentType = "application/csv"
Response.AddHeader("content-disposition", "filename=fred.csv")

This has been successful until recently.
One machine now opens the file into 1 column in excel.
Base set up: XP, Office 2000
Troubled machine does have SP2. Others SP1.
The regional settings appear consistent to working machines.
Regional settings English (United States)
List separator = ","
When he exports a csv file from excel it is comma separated.
Any Ideas? Have others resolved this issue?
Thanks.