Connection trouble!

Hey, I've been using Maxthon Portable between my computer, one at school, a friend of mine's and at school, because I have a research project and I want to make sure I don't lose any useful sites I passed by. But only one problem: I can't connect to the net. Then I tried other things, and NONE of my apps can connect to the internet, on any computer! My friend said I can play with his PC's firewall settings, but I can't get anything to work still. And on my own computer, I can't install Firefox Aurora because it says the download was interrupted. I managed to download the installer through Internet Explorer, but the installer can't download the updated version. What is going on?! I tried shutting Windows Firewall down, but nothing changed! I'm getting REALLY frustrated right now! Any tips, guys?