I have a website that serves up dynamically-generated CSV and XLS files.
On my workstation, Excel automatically launches when I click on either of
these types of files.
But once the file is loaded in Excel on my workstation, I am unable to
successfully create pivot tables (nor can I refresh pivot tables that are
already defined in any of them).

Here's what I do with the XLS/CSV files that have no pivot tables in them,
followed by the errors I get:
1. Click on the XLS or CSV link on the website. (Excel automatically
launches.)
Note: when the "File Download" dialog box arises, it says that the file's
name is "table1.csv", yet if I click "Open", the title bar in Excel seems to
believe that the file's name is "download.do" - which happens to be part of
the URL that served up the file.
2. Select a range of data, then choose Data - Pivot Table and PivotChart
Report...
3. Use the Pivot Table wizard to select "Microsoft Office Excel list or
database" as the source, select my data range, and tell it to deposit the
data in a "New worksheet".
This yields the following error in a dialog box:
"Cannot open PivotTable source file 'download.do'"

Here's what I do with the XLS file that already has a pivot table in it,
followed by the errors I get:
1. Click on the XLS link on the website. (Excel automatically launches.)
Note: when the "File Download" dialog box arises, it says that the file's
name is "table1.xls", yet if I click "Open", the title bar in Excel seems to
believe that the file's name is "download.do" - which happens to be part of
the URL that served up the file.
2. Navigate to the worksheet that has the PivotTable on it.
3. Right-click on the PivotTable and choose "Refresh"
This yields an error similar to the one in the previous scenario, although
somewhat more verbose:
"Error: Cannot open PivotTable source file '[download.do?
contentId=10&name=file_with_pivot.xls]Data'."
NOTE: The part between the brackets is information that also appears in the
URL that is used to download the XLS file. "Data" is the name of the
worksheet inside the XLS file that contains the range of data to which the
PivotTable refers.


One additional note:
In both scenarios, if I Save the file (making sure to change its file suffix
to ".xls"), I can then successfully refresh and create pivot tables.


Any idea why I am unable to get this to work without saving first?

Thanks.