Cannot Keep Internet Connection

I have a desktop that had issues, so I cleaned the hard disk and reinstalled the software like when it was new. I have updated all the windows and network card updates.When I first start the computer, I can connect to the internet for about 2-5 minutes then lose the connection. Often, internet explorer shows a screen that says the site is busy and try again later, but we can connect fine on other computers. Our internet connection comes from a DSL modem to a Cisco Valet Plus wireless router, however this computer is connected by a hard wire to a port on the router. I have changed ports, but have the same issue. The computers connected wirelessly stay connected.

I can restart the computer and the internet will work for 2-5 minutes again, but then do the same. If I go to ipconfig and release and renew, it still will not connect to the internet.