Cant download "anything" !!!!

Hello, i have had a windows vista home basic for a while now and have had an on going problem with not being able to download anything from the internet iv tried all of the suggestions in this forum but still nothing every time i try to download everything goes smoothly but then it stops and says something about windows defender so i tried turning off windows defender and that didn't work. so then i went to i.e. tools, i.e. options, then security, then i clicked on custom levels and went to automatically prompted file download and clicked enable. that turned off the windows defender thing that kept popping every time i tried downloading something but now when i try downloading, again everything goes smooth then the download just disappears im going nuts please if you can help it would be soooooooooooooooooooooooooooooo great.