That link is actually outdated; viewtopic.php changed to showthread.php ages ago. It was showing blank because our 404 error page wasn't working properly, now it'll show a real 404.
The problem that some people are experiencing with being redirected to a blank page when they log in is related to the daylight savings change, and not the forum software. Kind of hilarious timing, eh? I believe I've fixed the problem, so if you're reading this post and still actively experiencing a blank page on login, please contact me.