Sometimes when I'm afraid it may time-out on me because my post is too long, I have gone ahead and posted the message half-way through. Then I go back into it and edit it...either for additional content or sometimes just for spelling...just an idea that may help.
Another suggestion to keep from re-typing your longer posts is to copy the content (Highlight it then "control - C") before you submit it so if it has timed out you can just paste ("control - V") the content into a new post...make sense?
Another reason it may lose your tying is if you attach a photo that is too big.
Hang in there...