Connected to the internet but can't browse

Hello, I was just surfing on firefox one day and decided that I wanted to try out google chrome on my computer. I tried to download it directly from the source at google, but download of the installer would not finish. I then tried the setup that installs it over the Internet, but the installer would not proceed. It recommended that I change the settings on my firewall, which I did. After doing that no browser, whether it be firefox, safari, ie, or anything else, is allowing me to browse the internet, they just keep telling me that eithr the session has timed out or they could not connect to the server. I have everything that is checkable, I have run virus/spyware/malware scans, I've done the resetting of the Internet explorer options, I've also run the Norton remover. None of these things has worked. I also tried to run a system restore on my computer, but an "unidentifiable error" keeps it from working no matter which restore point I choose. I know it's not the network because one of the computers in the house is hooked up to the dsl modem while another one is connected to the wireless router, neither of which are working with my laptop. I really need some help to resolve this.