I am trying to edit a word document from VB.NET using for the most part this code:
How to automate Word from Visual Basic .NET to create a new document
I was experiencing the same issue and the problem area I found was "security configuration for Microsoft Word in DCOM". On the following link you can find a step by step guide to know how to config components in DCOM, repeate these steps for WORD, and your problem will be solved.
http://www.biocompsystems.com/_public/DCOMConfigurationStepbyStepForXP.doc
Thanks, Sushil Jinder