This is a simple matter of no.php.net being broken. The search
randomly picks a mirror in your country and sometimes it picks
the broken no.php.net as opposed to the working no2.php.net
I have sent a message to the maintainer [Stig Bakken :)].
Another broken mirror is us.php.net as it will do a Yahoo search
nomatter what you type:
us.php.net/echo -> http://search.yahoo.com/search?p=us.php.net%2fecho
That is because there is no such host as us.php.net. This is set on your own system to start a yahoo search. The same would happen for
http://nosuchhost.php.net/echo :)
Goba