I have a web server that allows a user to download excel files, these
files have a autorun macros that format the sheet on load.

The problem comes when the excel macro is creating a pivot table the
message

"Run-time error '1004':
Cannot open PivotTable source file
c:\Users\RobW\AppData\Local\Microsoft\Windows\Temp orary Internet Files
\Low\Content.IE5\Q4PYYXA\[Final%20League%20Position%20Bo"

and then the message box runs out of space.

If I save the file to the local disk before openeing it, I don't get
this message and the macro's run fine.

Why might this be happening and what can I do to fix it?

Thanks for any help.
Rob