Can't create file: Book1.xls error

[pfranz]

I have a user that gets sent an Excel file everyday. The sender always sends
it as Book1.xls. A few days ago whenever the user tries to open it he
recieves an error

Can't create file: Book1.xls. Right click the folder you would like to
create this file in .....

Even Save As a different file name won't work in various locations.
User can open any other xls file or any other file in general.

Any thoughts?

Patrick