I've noticed the same thing from time to time, but it doesn't appear to be anything too tragic. I rarely disconnect from the downloads in progress and they seem to all continue to get back up to their original download speeds within a matter of seconds. I'd assume it has to do with the cache on the computer as opposed to any malware that you are concerned about. There is a concerted effort to dole out malware to p2p users right now, but their effects are far more serious than the matter you mention. Most malware will generally alter your registry and the values set within it and no matter how many times you uninstall java and limewire and reinstall the programs, the affected registry will usually remain the same and the serious problems will continue to exist. I wouldn't worry too much with what you've observed with the speeds all dropping to zero as those are not an accurate reflection of the speed at the time. I have a meter and when this occurs to me, the meter is still showing the downloading as taking place at the same original speed. Like I said earlier, it could be how the cache is handled. It ain't broke so don't try to fix it.