Right-click the Excel file that you cannot open and select Properties. When the Properties dialog shows up, switch to the Security tab. Hit the Edit button to change permissions.

The first thing you should do here is to close all programs that are using the Excel file you are attempting to open. Please ensure the .xls file is not opened in other workbooks, add-ins, or apps.

Open Microsoft Excel and press "Ctrl-O" to bring up the Open dialog window. Navigate into the folder containing the files. Click the file type drop-down menu and select "Text Files (.prn,.txt,*.cvs)." ...

Locate the XLR file on your Windows 7 computer. Right-click the file and choose "Open With." Select the "Microsoft Excel" option from the list of suggested programs and click "OK." ...