The messages will always try and format to the width of your screen. The one exception, which is the problem that you are referring to, is if someone has one long word in their posting that is wider than the your screen window in which case a scroll bar is provided. It is BEBOP's signature with the long URL to the forum that is causing this on pages he posts on. If one posting forces a wide page then all other messages on that page have to follow the same width.

Maybe BEBOP can change it to a shorter version http://www.synthzone.com/cgi-bin/forumdisplay.cgi?action=topics&number=25 which will still lead to this forum and avoid the page width problem.