A family of Microsoft word processing software products for creating web, email, and print documents.
This issue may occur if the file association is not correct, try the steps mentioned below:
1. Download and save the attachment on the desktop.
2. Do a right click on the saved file.
3. Select Open With from the pop-up menu.
4. Click Choose default Program.
5. Select Word in the Programs box.
6. Check Always use the selected program to open this kind of file.
7. Click OK.
If this does not resolve the issue, refer the link below for file association:
http://windows.microsoft.com/en-US/windows7/Change-which-programs-Windows-uses-by-default
Ruchi Bisht