While there is a way for you to open two Excel workbooks at the same time, you can also open multiple spreadsheets in separate windows. Learn how!

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

If you launch multiple files by double-clicking their shortcut icons, or via the "Open" menu in Excel, the files will run simultaneously in one Excel window.

You must be able to open the corrupted workbook for the following to work: From the File menu, choose Save As. In Excel 2007, click the Office button.