I am using Office 2010 and I use this Excel file every day. This morning my office frozen and I need to shut down my entire computer. When I booted back up I tried to open my excel file and it suddenly changed from an .xls file to a .xlsx file and I cannot open this file. My laptop has Office 2007 and I cannot get the file to open on Office 2007 either. I have tried several other options and for the life of me I cannot get this file open. Can anyone help???