Dell desktop has a dell USB wireless adapter. System worked fine a week ago and now all of a sudden won't connect to the network. Doesn't even attempt to get an IP. It can see the networks in the area but can never connect. Repair doesn't work, reset TCP/IP stack didn't work. Uninstall and re-install adapter didn't work. Updated driver didn't work. System is running XP SP3. All the other systems in the house work fine. Router is provided by Comcast and uses WPA2.