Hi Cando,
Have to say I have often suffered from the diappearing reply.
Seems usually when you just pop off for a second to check something on a different site or such.
I discovered these 2 things which occasionally, but not always help. You should know, I am not technical, just desperate and annoyed like you.
Whenever you go anywhere away from the reply you're part way through, minimize it so it is a little window on the bottom of your screen and you can click on it and bring it back. You can then ramble about and it won't go anywhere, just wait for you.
Also, the reply window on rootschat does not have a button for "undo last" like on ordinary email. [Well not that I,ve located at least]
When a paragraph you've just finished disappears as seems to happen to me a lot you have to use the keyboard shortcut for undo last" which is ctrl+z. When you do that, it pops back again.
Anyhow, don't know if that's of any use.

Sue