A very good friend of mine, a well-known editor and writer, recently got bashed on Livejournal simply because he made a comment on a book review about an author's story, saying that said story didn't really work for him. There was nothing mean-spirited about it at all. Just a general comment. The story's author then proceded to get mean first, and eventually threatened my friend's life. I kid you not.
The plus side to this (if there can be one) is that the author in question pretty much killed his career by doing this on LJ, where all my friend's friends in the publishing industry (writers, editors, publishers) found out his real name. The authoroties were contacted, because of course, LJ logs your IP when you make a post.
How insane is that?
If you want to write, grow a thick skin and accept that you WILL be critisized. It is part of the learning process. And constructive criticism will help you become a better writer, by the way. Seriously, we could really do without the whackos.