@raja gujral
brother if a user take more than 15 min (i think so) to write a reply he is automatically logged out (for example you were searching something on the net and at the same time posting a query or a thread or you was on another website reading something to add to your post you will be log off from the forum ) the best thing is to copy your work if its a long post and if the error "you must be logged in to post new thread" login to your account again and paste the material in the reply box.
every forum use this policy and you are just being paranoid here nothing else usually bans are time limited for ten or more days no one can ban you for ten sec.