Check for updates for your Word here:
http://office.microsoft.com/en-us/officeupdate/default.aspxAlso check if any addin is causing the problem. Disable them. Go to Tools > Options > Other > Advanced Options > Addin Manager or COMM/Addins and disable the addins.
If neither of this works, check this post:
http://www.experts-exchange.com/Software/Internet_Email/Email/Q_22655345.htmljppinto