You need to ensure that IPv6 is enabled to set up a windows 7 homegroup:-

Start and type in Network into the search box. Then click on Network and Sharing Center.

On the left you will see "change adapter settings" click on this You will see your network - right click on this and go to Properties Here you should see IPv6 and IPv4 - they should both be checked.

You also make sure that Network Discovery is enabled on your Windows 7 PC's

Control Panel - Network and Sharing Centre - click on "change advanced sharing settings" on left hand side

Make sure "turn on network discovery" and "turn on file and printer sharing" are enabled.

You also need to make sure that the time shown by both PC's is the same.

You need to make sure "services" are turned on:-

Start - type in services" - in this dialogue box Double click on "services" Make sure that "Start up type" is set to "automatic" and click start to start the service

Make sure your network setting is set to "Home" Go to "Network and Sharing Centre" - look under "Network" -is it set to home? If not you can change it by clicking on the blue link.

Although most routers do support IPv6 protocol there is just the offchance that older ones do not - check your router.

Hope somewhere here there is a solution.