I recently installed Office 2011 for Mac on my MacBook Pro and am having compatibility problems with Excel files only, Word and Ppt are fine. When I open files that I created in my old Office for Mac, they appear empty, even though when I do the "compatibility mode" check, it says no compatibility problems are found. I encounter the same problem opening some .xls files sent to me by others, but not all. I can't find anything in Excel Help that addresses this problem. Does anyone have experience with this? The only workaround I have found is to import the spreadsheet into my Google Drive; then I can view it. But it is a pain to have to do this with all my files. Is there an easier way?