A window, or a banner at the top of the page? I'm not able to duplicate this problem as I don't have any computers with IE8 on them, but my advice would be to use something other than Internet Explorer 8, if you can. If not, I'd collapse the quick reply box so that the quote button uses the standard reply form instead.
I collapsed the quick reply per your recommendations and that seems to have done the trick. I'll try the non-IE8 option when I get home. It's my only web browser here at work.