When I'm pressing Ctrl+Enter on reply (creating new topic, not quick reply) the input data is cleared, page is reloaded and nothing happens.
I've encountered with this on my local board, then I tried to install new board from scratch and was able to reproduce.
Analyzing Fiddler sessions I found one difference: broken request does not contain Post field inside:
Btw, the issue is reproduced on phpBB forum, too.
Steps to reproduce:
Click on New Topic button;
Type any text;
*Expected: *Nothing or sending the message;
*Actual: *page refreshes with loosing all input data.