let us say the network adapter is working fine especially if it's for wireless adapter or NIC.
i think you need to check you IP going to start>run>cmd a black screen will appear. type ipconfig/all and check the IP if there is an ip for as long as it's not 0.0.0.0 or 169.x.x.x your good to go. you can also try to check if the network adapter is working by pinging it in the black screen type ping 127.0.0.1. Also try to check Browser settings on IE go to [IE7 or lower] [for IE8 a gear icon at the upper right hand side]Tool>internet options> Connections tab>Lan settings button> uncheck everyting and there should be no proxies. I assume you have the TCP/IP settings set to obtain automatically an IP adress to your ISP right? Try to also reset the IE settings under Advanced tab in internet options, hope it will help. Otherwise for deep and major technical troubleshooting you might need to got to start>run type services.msc [let me know if its helping or not] then I might do a little research for it.