I have a perplexing problem, and nothing I've found on the web has been able to resolve it. I am using Windows 7 Home Premium 64-Bit, and Norton Internet Security 2010 is installed. I have confirmed (more than once) that the active network is the "Home network", but when I try to enable Network Discovery and File and printer sharing under the Home profile in Change advanced settings, Windows keeps reverting the selections back to the off position. I am unable to share files/folders in Windows Explorer, and I assume this is the reason.
I have tried a number of things, including turning off uPnP in my DIR-655 router (as someone suggested), completely disabling the Norton firewall, deleting, then re-establishing the Home Network, but nothing works. My laptop, which is also Windows 7 Home Premium 64-bit connected to the same network, allows me to turn on network discovery and file/print sharing, and I am able to share folders/files under Windows Explorer on the laptop. But this issue with the desktop is maddening.