Forum Posting Etiquette (excerpts)
How to Be a Good Forum Participant: A Guide to Web Forum Netiquette
Do not "hijack" forum threads. Stay on topic and avoid directing the thread away from the current line of conversation, particularly if the original poster is seeking an answer to a question.
If you'd like to discuss a different issue or problem, start a new topic / thread on the forum.
When a particular topic has been requested to be addressed by certain knowledgeable forum members, that request should be respected.
Remember the forum purpose. It's important to keep this in mind. New topics AND responses should be relevant to the forum's stated mission.
While it's okay to make a casual comment, share an experience, or make a joke, the comments you make should still be relevant and on-topic. If in doubt, read this list from the top again.