I've been having this problem for awhile now. Downloads start okay and then just stall a little way in. Sometimes they slow down to a crawl and then stop, and sometimes they just stop cold. I've done a number of virus/malware checks and the computer is clean. I can get around it by using a download manager like Flashget, but sometimes the thing you are downloading is an auto-download withing a game or an application and you can't used Flashget. I am running Windows Vista. I am connected to a router, but even when disconnecting the router the problem still persists. Turning off my firewall also has no effect. Streaming videos like YouTube works fine. Just downloads are the problem. Kind of maddening, at some point I guess I'll just have to reinstall Windows, but maybe someone here has suggestions.