It does this. It's a nasty glitch. Always highlight and hit CTRL c to copy your text. Then when it goes poof you can just start a new entry and hit CTRL p and have it back. It usually only does the first time you post. It seems not to like it if it takes you more than five minutes to write your entry.
May 10th, 2013 at 10:36 am 1368182209
May 10th, 2013 at 03:11 pm 1368198705