Testing on IE9 phpBB, I met a problem trying to use "quote" function.
How to reproduce:
 choose whatever topic you want
 click "answer" button
 under the posting box, there is the topic review box. Select a multiline text in the review box and clic on "quote" button
 you should see formatting problems (text disappearing, new line characters also disapper, ...)
However, when clicking "quote" button directly on messages list (on step ), everything is ok.