This month's monster security patch for Office breaks Excel when it tries to open HTML files, and it seems unlikely Microsoft will fix the problem Excel users are reporting an odd bug in the way ...

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.

You can also have Excel open automatically. Disable Start screen and automatically open a blank Excel workbook By default, a Start screen appears when you open Excel (see the screenshot below). The ...