Fix my downloads?

When I try to download from any web page, like download.com, the download will start but then it will stop downloading, like the internet has dropped out and if I try to download the same file again it will drop out at a different spot. But I can go back to the browzer and open up new browser pages without a problem. It is starting to frustrate me when I try to download antivirus and windows update that are over 10mb, and when it gets to 7mb it will freeze the download. I haven't even gone over my download limit.