Cannot open Office 2007 docx document!!

I haven't had sleep for more than 30 hours now.. We are trying to rush this manuscript out for M to vet before he goes off on vacation. Been a hell of a week.

Anyway, Ja sent me her Word docx and I couldn't open it in Windows Office 2007. Got this error:

Tried all the ways on this error warning but to no avail. But I really need it to work. So I sent emails out to Ja and A, they re-sent me the original files >_<. A said he got it to work by converting to PDF format (right-click) for Mac. That is a good solution for Mac (if you guys are Mac users), except that it's not editable now and that doesn't work for me because Windows needs to still open the file for conversion; they use Mac, so maybe that was a good workaround but truth be told, I have no idea about Mac .

Solution/workaround:

An epiphany suddenly occurred to me. Without even thinking twice, I changed the extension "docx" to "doc" and voila! Open sesame indeed! Then I just re-saved it as a "docx" Office 2007 format file.

Speculation what has gone wrong:

1) Maybe the saving process by Ja was somehow interrupted on her Mac.

2) Somehow encoding got scrambled.

3) Just bad luck.

Just wanted to share a quick and dirty way to get around this problem.