Have you upgraded your Microsoft Office? If you use Word 2003, you might noticed that you cannot open it in Word 2007. In Word 2003, the file that you save is in .doc format meanwhile in Words 2007, it in .docx format. You cannot open .docx format using Word 2003. What you can do is install Microsoft Office compatibility Pack for Word, Excel, and PowerPoint 2007 file formats.

By install this, you can open .docx format using Word 2003.You can download it here. Before you install this, make sure that you update your window. You can update it here.