I have MS Office 2007, Windows 7. When I double click on an XLS file, Excel opens up but it is just a empty Excel program. It is similar to opening up Excel and then just closing the book1 that opens up automatically. Just a grey background. Also I can't open up XLS files by doing File > Open or dragging XLS files into an already opened Excel. And double clicking an XLS does not work. I tried doing a detect and repair on excel but that did not seem to fix anything. Any ideas? Thanks!