It might work fine if you have Excel but it doesn't if you use another program to handle .xls files.
MS Works spreadsheet which is the most common on home computers without business applications gives this: "The document is password protected or encrypted. Open it in the application that saved it, remove the password or encryption, then save it again. Then try opening it in Works."
602PC Suite opens the file but when you try to use it by clicking on a cell, you get the message that the cell is locked.