You could try limiting your upload slots according to your speed as Grandpa suggests here
http://www.gnutellaforums.com/showpo...94&postcount=2

It's possible that it's ISP related, some people have had trouble with their ISP disrupting uploads.
Within LW tools > options > bug reports > view example. Scroll down to 'recieved incoming this session'... is it true or false? False indicates a problem with people being able to upload (usually a firewall).