I got it in the neck from my son, when I changed my Firewall settings to prevent other computers' incoming comms via Limewire, which created the same effect as you have described.
By creating a new drive partition for his music downloads via Limewire (a vain attempt at some security! :-), and allowing all access via Limewire to that partition only, the problem went away.
Would suggest that you check out your firewall settings as a consequence.
But would also advise very strongly, that you consider setting up a separate partition for your downloads, as peer-to-peer services such as these are prime targets for internet ne'r-do-wells.