Problem with url loading: browser goes black

Hi,

I have an instance of nsIWebNavigation, using the code below I can
load any url and browser appears in a jframe bound to the browser.
webNavigation.loadURI(url, nsIWebNavigation.LOAD_FLAGS_NONE, null,
null, null);

In a very rare case of some urls like www.gromas.dk a strange
situation takes place: url seems to start loading and even for a
millisecond some elements of page strat to appear, when suddenly the
window goes totally black just like if there was only a black
background loaded.
Did anyone see something similar in your applications?

Thanks in advance