Here is the entire application which generates the error:

Sub bob2()
Dim owb As Workbook
Set owb = Workbooks.Open("C:\temp\test-import-data.xls")
End Sub

Can't get much more stripped down than that. I can open
test-import-data.xml just fine in Excel but when I execute this functon
I get 1004 "Application-defined or object-defined error". The file is
created via an output from Siebel. But it is in Excel format. We are
using Excel 2003.

Any ideas?

If I open up the excel document it will automatically close it when I
call the open and still throw the errors.