Help, network discovery will not turn on?

I have a dell xps 435T running windows 7 Ultimate. It is my primary computer as well as being the primary computer on my network. When I turn on network discovery, hit save, and exit, it turns back off. I can not get network discovery to stay turned on. I need to be able to connect to this computer from other computers and devices in my network, but cannot do it with network discovery turned off. Any assistance would be greatly appreciated. Thank you, Jim