My computer keeps saying I need to connect to a broadband network?

My computer is hooked up to the Internet and I can get on the Internet, but after a few minuts a box will pop up saying I need to connect to a broadband connection. So I hit cancel and if I'm watching a YouTube video it will stop and say a error has occurred. So then I have to refresh the page then another message comes up saying 'Internet explore had to go online to open page, go back offline?' So I hit cancel on that and the same thing happens again 30 min later.