A relative of mine has a computer running Windows Vista (64-bit) which has Office XP (which I think is Office 2002). I know that beginning with Office 2007, the default file extensions for Word, Excel and PowerPoint are docx, xlsx and pptx, respectively, and that prior versions of Office cannot open those files unless they install the Office Compatibility Pack.
This relative was recently emailed some docx and xlsx files. I installed the Office Compatibility Pack and now they can open the docx files. But they still cannot open the xlsx files; when they try they get an error message saying "This file is not in a recognizable format" and then Excel opens but its full of gibberish (see screen-shot).
I thought maybe they needed to have have Office Service Pack 3 installed. I checked Windows update but it said there were no updates available, which made me think I must already have it installed. But just to be sure I installed the service pack anyway. No change.
Why can't they open xlsx files?