Might be the settings.
Some dial ups have a "inactivity setting". This could be set so you automatically log off because you haven't had any activity, (Clicking on something, changing web-pages). So, even if your typing up a post, depending on the length of post, you haven't done anything in the set time, so you get logged off automatically.Its a security thing thats mostly on dial up servers. You can set it yourself, but its been soooo long since I was on dial up, I forgot how to do it.
I had that same problem when I was on dial-up. Don't get it at all since I got broadband.
Gee...I hope i wasn't babbling there....