Same problem here. I have a seperate server that contains all of my movies and photos. ATV will not recognize this computer. We have two seperate laptops that work fine with any movies stored here but not on our server. I've received no help as of yet.
Same issue. latest version of itunes (11). latest version of Apple TV software, ios6 on ipad and iphone. 1 in maybe 15 times I get a home share connection. all devices using same network, all devices using same apple id. it's not that complicated. but it's not reliable.