Katie Bascuas gets some advice from Martha Jack on how to handle negative comments on your blog, and the first piece of advice is to have a plan before anything happens.
Know your audience. Whenever I’m dealing with a negative comment online my first question is “who is this person?” You may not know them, but others in your organization may have dealt with them. You want to know things like how well-known they are in the industry, are they known for causing trouble, are they the type of person who is never going to be made happy, before you decide how to proceed.