Pipex are known for p2p traffic shaping...
http://www.gnutellaforums.com/connec...-limewire.html
That padlock notice you see at the top of your searches is to notify you of a particular search result that contains a virus...
It's a 75.7 KB .exe & shows up as "Urgent LW update - download & install now". If people download that thing they could end up infected. To try to prevent careless people from downloading a dangerous file, the warning banner was added to LW's interface.
The padlock symbol doesn't apply to music or video etc, only to LW updates...