If you are able to connect through another network, that indicates that you may not be consistently connecting through your own network. You need to make sure your computer is set up to connect only to your own router by specifying your own network as primary, so you do not access someone else's intermittently, because their signal may be unreliable. Also make sure you set up your WPA encryption code so that no one else can access your network. These configurations are done with the wireless utility on your computer. This may or may not be the cause of your problems, but just one of many possibilities.