Internet Not Working?

My internet, DSL, has been not working properly the past couple weeks on my PC. There would be periods of time where the internet would not work. For example if I click on a video on youtube to view, the clip would start buffering but stop midway, quarterway, etc. The clip would not restart buffering unless I refreshed the page. I've noticed that this also happens when I load a regular page as well. BTW, this started happening when I got a wireless router for my house. But routers aren't supposed to do this right? Another thing I did a virus scan so I don't think it's a virus. But it might be?