After fighting for 2 days with this issue, and tried a lots of things - including the solution above, this worked for me.
I have a MacBook Pro with OSX Lion.
I was trying to connect to Windows 7 Professional within a domain.
My W7 login was the same use to log into the domain and also a local (\\my pc) admin.
I shared \\my pc\c.
Nevertheless I couldn't access my files at \\my pc\c\users\user xx
I solved the issue like this.
1) unregister \\my pc from the domain
2) activated the admin account - local security policies -> local policy -> security options -> Accounts: Administrator Account State (enable it)
4) Log as the local admin (\\my pc) and define a password.
5) Rejoin the pc to the domain
6) On the C: share give permission to \\my pc\admin with full control (remove all other - including any domain accounts if any)
7) log out and log in with the normal user (with the domain account and profile)
Now on MAC using Finder: Go->Connect to Server
When asked for credentials use your local admin/password
And it's it.
Now you can access the all the C: drive and all user files.
Hoppe this helps.