Downloading Problems. when i try to download a program from the internet, or try to attach files

Question

when i try to download a program from the internet, or try to attach files to an web-based email, the file won't attach or download. My desktop seems to refresh itself, but nothing happens. After clicking on a link to download something from the internet, a pop up comes up saying either save file or cancel, and after clicking save file, my desktop refreshes itself, but doesn't download anything.