From Mexico.purplecow.org
So, you can't access C$ on Windows 7 with smbclient? And this breaks your backup software? Yeah.
Step 1. Uninstall "Windows Live Essentials". Yes, it probably came in with an IE update or a service pack. It's worthless anyway. Remove. It somehow manages to break authentication, which tells me it is trying to do something very crap.
Step 2. regedit time.
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- DWORD: LocalAccountTokenFilterPolicy
- Value: 1
On Windows 8, you may see failures with extended debug information like:
- "SPNEGO login failed: Invalid parameter"
An updated samba (and thus smbclient) may fix this, otherwise you can try adding:
- "client use spnego = no"
to smb.conf. This may impact other connectivity, so test it in the model first.