Slow Cable modem upload/download
 

I am experiencing a very strange problem with Gnutella. When someone tries to download something from me their download speed progressively gets slower and slower until finally it says "Incomplete transfer". My download speed (when I download) is also very slow. I want to share my files but I can't because no one can complete a download from my computer. What is the problem and how can I fix it. I have an extremely fast cable connection.

Thank you