My Internet Stops working But Only On My Laptop

Someone gave me a new laptop and since the first day I got it I've been having problems with the Internet. It works for some seconds, sometimes even minutes, and it would suddenly stop totally working until I disconnect and connect again (and sometimes that doesn'd work at the first try). I gues it is a problem with the laptop because it worked when I connected it to a friend's wi fi. And it is not a problem with the router because the rest of devices in my house work fine. I downloaded CCleaner to see if it worked but nope.
Can someone help me? It is really frustrating and I've been trying to fix it for the last 2 days and nothings seems to work.
The computer is a Lenovo and the operating system is Windows 7.
Thanks.