Likely a badly closed piece of code in a JMod sig or something similar (wouldn't be the first time), or badly implemented jquery code which I've experienced on the forums previously.
I seem to remember there were quite a few issues when the quick reply box (bottom of page) was first implemented. For instance the textarea was about half the size of the actual background image that it was meant to sit on, which caused some repeats in the image display at the bottom of the screen. Overriding some of those styles *might* resolve the issue.
27-Dec-2013 01:39:05