No idea, going to need much more detail information to track this down.\
Can you update to bbPress 2.5 first and let me know if that fixes your issue.
updated to 2.5 and it still happens. A user sent me a screen shot of what she wrote and what actually appeared in the message. And only the first line of the message was included in the message published. The rest was erased.
Seems I cannot attach the screen shot to this message.
paste here your site url or screenshot..
just remembered that I had to answer this one. It seems, that it was because she was trying to put in some smilies and that was not well received by the forum. Not sure why but when she put in the smilies it made the rest of the message dissapear.