Why can't I edit my post?
Once you write a forum post, you have an hour or so to make any refinements, and after that it's not editable anymore.
We used to have a longer editing window, but we found it was mis-used by folks to completely change the meaning of their post (as opposed to fixing typos/clarify meaning). This made reading the forums difficult, especially when a 100 words of post have been replaced with "." !