Some users report problems after upgrading Office or Windows to an Office 2010 / Windows configuration. Word sometimes no longer recognizes DOCX files. This problem often results from old registry entries connected with a previous Office installation. Registering Word 2010 solves the problem. With the right command, this simple process requires very little user input.
Instructions
Click the Start button in the screen's lower left corner.
Type "winword /r" without the quotation marks in the search bar. Press "Enter."
Wait as the Microsoft Office Professional Plus 2010 window configures your installation, re-registering Word.
Restart Word 2010.
Read more: http://goo.gl/VWSo8
