This may be because you are composing in plain text rather than HTML? As a remedy you could try the following: 1.Go to Preferences > Advanced and click on 'config editor'. You will see a warning message, but proceed anyway. 2. Type 'wrap' (without the quote marks) in the search bar. 3. Double-click on the parameter 'plain_text.wrap_long_lines': this should change it from 'false' to 'true' and also make it bold. 4. Exit from the config editor, close and restart Thunderbird. If that doesn't cure it you can go back into the config editor and reset that parameter to the default (double click it again).

I changed the "plain_text .wrap_long_lines" to true and that didn't change anything so I changed the "mail.compose.wrap_to window_ width" to true and that didn't help either. Is there any point in changing both lines back to false?

I really appreciate your help. Any other ideas?

You're not replying to a message when this happens, are you? There's an old thread here about this phenomenon in replies: http://forums.mozillazine.org/viewtopic.php?t=620097#3219442 Do you get this behaviour when composing a completely new message both in plain text and in html?

It happens both in a new message and in a reply. Also I just noticed my inbox is not displaying senders. Just subjects and time and date. I went to a Moz backup of Thunderbird from 3 months ago and restored and still the problems persist. Perhaps I should backup my address book and uninstall TB?

Somehow I fixed my problem after several sys restores. I restored address book from backup and now everything is fine. I just wanted to thank you for taking your time to help me. Jill

Well thank you. :) It's nice to know when things work out!