The other day I had the need to browse out to one of my Windows 2008 R2 servers using one of the default administrative shares, such as C$.
Trying to browse out using a UNC path of \\SERVER1\C$\FOLDER1 and I received an error “Access Denied”.
Trying to map a drive to \\SERVER1\C$ also returned an “Access Denied”.
After a little research, I learned that UAC (User Account Control) is set up to not allow access to the default shares remotely.
There is even a Microsoft KB article on this here.
To fix this issue and enable, simply launch RegEdit and set the following key:
0 = build filtered token (Remote UAC enabled)
1 = build elevated token (Remote UAC disabled)
By setting the DWORD entry to 1, you will be able to access the administrative shares since the remote logon token will not be filtered.
Hope this helps!