Home sharing problem

I have 2 PCs, a Laptop, an Apple TV, and an iPhone. All of which I want to use home sharing with

One of my PCs has my full library stored on it. It is a Windows 7 PC

Home sharing works fine to the iPhone and the Apple TV. When I try to pick up home sharing on the Laptop or the other PC I cannot pick them up. I have gone through the Apple troubleshooting steps but they don't seem to help and I can't see why the iDevices should work but the PC and Laptop doesn't

All computers have Win7 installed. I have disabled firewalls etc. somewhat annoyingly I can see the Laptops library on the PC but not the other way around. All devices are on the same network I can't see why this should be a problem.

Any help appreciated. Thank you