First problem I can see is your ISP is TalkTalk. From memory they block/shape bandwidth for p2p sharing over various times of the day. You will find TalkTalk listed here in point #5 http://www.gnutellaforums.com/connec...-limewire.html. (click the link in that post to read more about TalkTalk)

So yes it sounds to me like whilst using LW, you pass that point in the day (time of day) when TalkTalk's shaping on p2p begins & your bandwidth drops. This would only apply to using p2p sharing software. So this will affect LW & any torrent program you use.

For your software firewall, make sure XP firewall is turned off, & you have an exception for LW in Kerio's firewall; Setting up an exception for LimeWire in your software firewall (click in link)