Network Shares
I also had problems connecting to network shares with RC1, which I dont remember having with the beta so I formatted and reloaded with the beta and problem is gone! There is something odd with RC1 connecting to network shares over Beta. I think it has to do with NTLM and how it's set under network security because if I change that it works.
This problem is where you can see other machines on the network but when you click on them it will not show you any shares and you will get a login dialog which will always fail. It even fails to view shares that open to the world!
Matt