Cannot access administrative share (c$) on a Windows 8 PC from Mountain Lion
Administrative shares have been disabled in Windows Vista and later versions of Windows for security reasons.

According to Microsoft Support Knowledge Base article 947232, you can do one of the following:


Create your own shares with the appropriate permissions (recommended);
Run the Microsoft Fix It to perform an automatic workaround; or
Add to the Registry subkey HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System a DWORD (32-bit) Value LocalAccountTokenFilterPolicy entry with the value data of 1.