Reset homegroup

I had a network with 1 home group. The primary computer that housed the Home Group I did a clean install on. I installed Windows 7 64 bit Ultimate. The other computers on the network are wirelessly connected laptops.

I did not unjoin the laptops from the home group before I did the clean install. I have subsequently un joined all the laptops.

When I go into Home Group on the newly installed Windows computer it says that " Brian on the-core has already created a homegroup would you like to join it. " the-core is the name of the computer that I did the clean install on that originally had the Home Group. Obviously that home group is no longer in existence. How do I erase the settings that are telling the computer in the network that there is a homegroup in existence when there is not?

Hopefully that makes sense. Thanks in advance

I think I have the exact same problem, I've been trying to delete preference files on the new computer, created a new account to replace a buggy old account and the other computer on the network (win7) has homegroup with the old account info. I've been trying to start Peer Name Resolution Protocol with a resulting error saying :

Windows could not start the Peer Name Resolution Protocol service on Local Computer. Error 0x80630203: Unable to access a key.

Did you have to reboot both machines for it to resolve your problem? I unJoined the homegroup, but I still get the error.