If the Windows 7 or Server 2008 (even R2) is not in a domain but in a workgroup, you may have administrative issues trying to access C$ etc.

Google found me this:
http://blog.hansmelis.be/2009/09/06/administrative-shares-in-windows-7/

A simple registry change and away you go. You do not have to reboot, but after the change you might have to wait up to a few minutes for it to work.

Those who have experience with NT-based operating systems on a network will certainly be familiar with the concept of administrative shares. If that doesn’t ring a bell, you access them like \\computername\c$. With this intro and the title of this post, you might be alarmed or enter panick mode fearing they might be gone in Microsoft’s latest OS iteration. Well don’t go into cardiac arrest because they are still there… but of course not without the odd problem.

Windows 7 still creates the administrative shares on install, but you can’t use them out of the box. First of all, you need to have File and Printer Sharing enabled. And the way to do that has once again been changed:

Open the control panel.
Go to Network and Internet.
Go to Network and Sharing Center.
In the left column, click on Change advanced sharing settings.
There are two profiles. You probably don’t want this on when you’re on a public network so open Home or Work.
Under the header File and Printer sharing, select the Turn on… option.

And now your administrative shares still don’t work 😛 You’ve just completed step 1 which implies there’s at least a step 2 and here it is: you also need to change the registry.

Click on the orb (= the round button with the Windows logo in the taskbar) and type regedit in the search box.
Open the registry editor.
Navigate all the way to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System.
Right-click in the pane on the right side and add a new DWORD (32-bit).
Give the new setting the name LocalAccountTokenFilterPolicy.
Double click on that setting and give it a value of 1.

It’s probably wise to reboot after doing this, although it might not be needed. I’m not sure if it works straight away because I rebooted without trying.

Anyways, if you’re lucky you will be able to access administrative shares after performing these steps. If you’re unlucky, like me, doing all these things appears to have zero effect at all. Once again don’t panick, because there’s another hint/tip/solution coming your way.

Somewhere at some point during the installation or configuration of Windows 7, you will be asked to do something with a thing called Homegroup. It’s some weird new sharing tool that looks OK but isn’t quite what you’re used to. Once you have enabled that feature, you won’t be able to use the administrative shares. So the tip is: disable the homegroup feature.

Open the control panel.
Go to Network and Internet.
Go to HomeGroup.
Click on the blue link Leave the homegroup.

The popup dialog should point out itself, but I believe I picked to first option. Once I had left the homegroup, the administrative shares started working again.

I hope this post can help anyone who experiences the same problem.