The 'default document' you see when you start a new document in Word is stored as a template file called 'normal.dot'
This file has become corrupted. You need to replace the file by following these instructions:
http://www.vlerick.be/helpdesk/our_services/fa q/software_solution/microsoft/word/faq_restore _correct_normal_dot.html
The 'wmv' format refers to Windows Media Video files. As the name implies, these are video file and they should open in Windows Media Player. However, Windows Media Player needs the correct 'codec' to play certain videos. Finding the correct codecs on the internet can be extremely tiresome. (As soon as you think that you've got all of the required codecs for any video file you might receive, you come across another video file which requires yet another codec).
The solution is to use a better media player than WMP. Almost anything is better than WMP, but these two are the most popular (and versatile) free alternatives:
http://www.videolan.org/vlc/
http://www.gomlab.com/eng/
Chris