Pipex Homecall are known to throttle p2p...Take a look at Birdy's posts in this thread...
http://www.gnutellaforums.com/showth...light=homecall
I'd say you have popped up on there radar as a heavy downloader and they have now throttled you....
You could try changing your listening port number to something between 49152 up to 65535, try this one 64049....