Homegroup is not functioning

We have 3 pc's, 2 laptops on our homegroup. I recently upgraded one of the pc's and couldn't get it connected again to the homegroup. Since then, I've tried the suggestions on the forums, and still get errors. I'm unable to leave/remove the homegroup on the host pc. I can't view/print the password or change it. We are literally crippled here. So used to accessing the network and moving things back and forth between the pc's.

Try removing the idstore.sst file from the following location:

C:\Windows\ServiceProfiles\LocalService\AppData\Roaming\PeerNetworking
Windows should rebuild the file after reboot.
Then try leaving and rejoining the Homegroup.