|You did tell us what version of Word your running....|
If your running Office 2007 then:
Running Microsoft Office Diagnostics from the Start Menu
Click on the Start button
Click All Programs
Click Microsoft Office folder
Click Microsoft Office Tools
Click Microsoft Office Diagnostics
Click Run Diagnostics
If that does not work, then 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
You may need to use the complete path name.
This launches Word with a clean, empty template and no add-ins.
If Word works 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 the file normal.dot and delete it.
If there is more than one, rename or delete ALL of them.
When you launch Word, it will look for normal.dot and since it can't find it, it will recreate a new clean one.
Be aware that 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
For your Add-ins:
On the Task Bar,
Templates and Add-Ins
Just uncheck them all and start Word with a new one checked until you run into trouble.