I think a person who says unkind words towards a person using the computer is very unethical. People who write things like this, normally do this because they have low self-esteem and need someone to be sad to make them happy. To my opinion i think a person who write unkind words about another person should be given a warning at first and the second time the should be removed from that particular website for good. Saying bad things about someone is not a very clever thing to do because of your anger towards someone else.
I would feel very embarrassed if a persons said something mean about me over the phone, email or a online discussion. I would definately be mad as well, so i'm guessing my first action toward this would be to argue. Even though this is not the wise and smart thing to do this would be the first thing that come mined.
There is not much of a difference between a phone and a computer because they both keep everything you write,send, say or do. The only slight difference about a computer is that the things you do, say and write basically stays there forever for millions of people to see. This is a perfect reason for someone to have a responsibility towards there action. The things you do on the internet can also prevent you from getting a job, so it's best to do the right thing at all times.