HELP! Network access down!

This is weird! was on the computer last week working great the next day NAda..no network and no internet on my Windows x64, on checking things EVERYTHING worked,pinged ok went to XP it worked as it should,it is where I am now! all tests passed yet I cannot access the network or internet on Winxp 64 pro!I had this happen before and had to reinstall it! now it,s doing it again!I,ve checked a few things and it tells me the basic link is connected to the network,I have Comcast! 8meg
a LinkSys G Wifi to two 1 gig LAN Hubs! all other computers are working fine as is Vonage(IP phone)

Cheers Dennis