I have a question that many people are probably wondering about...

I have found that if I enter the name of a file I want to download on my search, the file shows up fine. Some of the time it downloads okay (from one host), but other times it says "needs more sources." It seems that during both scenarios, there is only one host on with the file, but sometimes it downloads and sometimes it doesn't. Is there any way to fix this problem or speed up the downloads? Why is my computer doing this?