Please remember that people all over the world are reading your words. Do not attack people if you cannot persuade them with your presentation of the facts. Screaming, cursing, and abusing others only serves to make people think less of you and less willing to help you when you need it. If you are upset at something or someone, wait until you have had a chance to calm down and think about it. A cup of coffee or a good night's sleep works wonders on your perspective.
Hasty words create more problems than they solve.
Try not to say anything to others you would not say to them in person in a room full of people. Maybe it is a case of the software not working, or a control message escaped, or maybe one of the users at that site has done something you feel requires comment. By being civil and temperate, you are more likely to obtain their courteous attention and assistance. This group quite possibly includes your boss, your friend's boss, your girl friend's brother's best friend and one of your father's beer buddies. Information posted on the net can come back to haunt you or the person you are talking about.