During the normal week,this site works onley 3/7 days for me. On the rest of these 4 days clicking on this site link provides me outstanding view: SITE IS UNAVAILABLE
i'm not the only one! here as well, every now and then the site won't open but i open other pages normally.
i guess you're using t-com's dsl, right? it's due to them, something with them and DNS server. not too long ago, in the bug thread, i reported it and martin explained it to me. the easiest solution i found was to kill your dsl connection and reconnect after a few seconds. after a few attempts the site loads for me.