A page that looked fine in the last version does not look correct at all in 3.6.3, although it looks fine in both IE6 and IE8

This is a log-in page, which points to our email registration software's server (Tikit's Emerge Reaction Server). If you open in it in the last version of FF, it looks as expected. The page renders fine in IE6 and IE8, and all our other website pages (www.mofo.com) render fine in both ver. of FF - its just the pages that point to our emerge-reaction server site that won't render properly. Tikit says we are the only user having this problem, and they don't know what the problem is caused by. Help!? == URL of affected sites == http://emerge-reaction.mofo.com/reaction/RSLogin.asp?eventId=TOPICS