3.5.1: Blank page visiting http://cajik.paleo.cz

[Pavel Troller]

Hi!
  I would like to ask, whether somebody else gets a blank white page, when
trying to display http://cajik.paleo.cz . I just noticed it. The page
is not valid, but it displayed well formerly, so it looks like a regression.
This page contains frames. All of them are visible when browsed separately,
excluding http://cajik.paleo.cz/cajik/chat_index.phtml . It also displays blank
page, probably causing that all the page displays as blank.
Should I enter a bug, if it gets confirmed by somebody else ?
      With regards, Pavel Troller