I have that same problem. Now, to save time, I automatically copy before I go back. But of course you lose all the brackets for colours etc; in fact, when I remember, I type the message in Word first then I have all the details ready to copy! But it is a pain. I think it must time out somehow because it doesn't happen if you're quick enough. Murphy's law dictates that the longer and more complicated the message the more likely you are to lose it.