I've just installed the RC and it automatically joined me to a homegroup... when I try to find out the password to the homegroup the box comes up blank !! when I try to change the password it just hangs up when i click the next button.... I've tried the homegroup troubleshooter and it seems to think that my 3rd-party firewall (Avira) is the culprit, but I've disabled the entire firewall and it still happens... other computers on my network can't create a new homegroup because they detect mine and I don't know the password!!!! ....very frustrating .....

You may have created a HomeGroup on this computer. If you would like to remove it, click Start->Control Panel->HomeGroup. Select Leave HomeGroup and the HomeGroup will be removed. Then, you may try to re-create Home Group without any firewall and anti-virus. could you obtain the correct password when you re-create the HomeGroup?Arthur Xie - MSFT

That's just the problem, It won't let me leave the HomeGroup. It says windows cannot disconnect my computer from the homegroup.

I suggest that you temporary disable the anti-virus and firewall. Then check the result. If the issue persists, I suspect that related system components or Registry entries are corrupt. You may try In-place Upgrade to repair the system.Arthur Xie - MSFT

Thank You for your help - I did In-place upgrade and now my system is working perfectly. I had tried to disable the firewall and eventually uninstalled it completely to no avail.... Now my HomeGroup is working like a charm!! :)