The two types of posters that are the most irritating...to me at least are:
A- Makes a new topic asking for help, gets several replies on how to achieve the fix...and the original poster never bothers to respond back.
and...
3- Makes a new topic asking for help, replies to his/her own topic with "never mind, I figured it out" without explaining what they did to figure the problem out in order to help someone else with the same problem.