This past weekend I spent some time troubleshooting an Xbox that was failing to download the latest Dashboard update for Xbox Live. Besides aborting the download, the console would sometimes also drop its connection to the router, giving an impression the wireless adapter attached to the Xbox was faulty. In fact, networking on both the Xbox and the router were working fine.
In this case, the console showed error code 3151-0000-0080-0300-8007-2751 that can indicate any of several potential problems. The root cause: A corrupt second profile on the Xbox. Deleting the bad profile unblocked the Dashboard update and restored normal network connectivity of this Xbox.→ See also - Xbox 360 Network Troubleshooting