What does it mean when you are "still downloading" but the speed of transfer drops to 0KB/s?

I also have an activity light on my hard drive, and no activity is taking place in the background, so I have to assume it really is 0KB/s. I usually get disconnected at this point and the download resumes, but sometimes, and that is what I am confused over, the download just sits there and does nothing. I read in another thread that others are having a similar problem. Also, as I write this my modem is acting like it is transferring data, yet I have no searches going.