Start Word in safe mode and check how it works.
To do that, close Word. Click on Start – All Programs – Accessories – Run, and in the open box type in winword /safe and hit ok. (Note: There is a space between winword and
/).
If application safe works, then refer to the steps mentioned in the following article and check:
http://support.microsoft.com/kb/921541
If issue persists, you may
restart the system in Windows clean boot and check the results.
Note: Make sure you restart the system back to Normal mode after troubleshooting.