Internet says it is connected, but it is not.?

I recently reinstalled Windows 7 on my machine. It used to work fine until my friend downloaded some Mallware, so I had to do a system wipe. All of my drivers are updated. When I go into the network sharing center, everything looks right. I can connect to my unsecured wireless network and it says everything is fine. But when i go onto the internet, it will work for about 20 seconds then just stop. It will come back on after a minute or so but still only last 20 seconds. If I try to download anything, it fails because of this. I put mallware bytes on a flash drive and ran a full scan and it did not turn up anything. Thanks for the help.