Seems like it's read-only for some reason. Does it say "read-only" in the title bar? If you use File>Open and type in the filename, can you choose both "Open" and "Open (read only)". Do they work differently?
http://answers.yahoo.com/question/index?qid=20080218082010AAcfUSN mentions the possibility of an expired trial copy. That seems unlikely for Office XP now.
Other things you can try:
- delete your default template normal.dot (it's surely there, although some people have some trouble to find it)
- uninstall and reinstall Office from the CD
I have a Toshiba L300-EZ1502, Microsoft XP professional
I am unable to type anything in any word document. Even if I open a new document it gives me the message at the bottom that the "selection is locked". This happened after I closed a document and then re-opened it a few minutes later. How do I unlock the entire application? I looked around for a while on the application and almost all of the buttons are inoperable.