It could be your global template is corrupt or there is something loading automatically in your Word Startup folder that is misconfigured or corrupt.
Go to Start
Click on Run.
Type winword.exe /a
This launches Word with a clean, empty template and no add-ins.
If Word launches OK, it is probably either a bad normal.dot file or a corrupt add-in
To get a new clean template, close Word and do a search of your computer for normal.dot file and delete it. If there is more than one, rename or delete ALL of them.
Now, when you launch Word, it will look for normal.dot and since it can't find it, it will recreate a new clean one.
In XP, the normal.dot file is a hidden system file and may not show up when you do a search for it.
If you are unable to find it,
Go to My Computer
Click the Tools menu
Choose Folder Options.
Click on the View Tab
Put a check where it says, "Show hidden files and folders"
and uncheck "Hide extensions for known file types"
and "Hide protected operating system files".
If you still can't find it, look here:
C:\Documents and Settings\<your user name>\Application Data\Microsoft\Templates
See if that helps.