I'm setting up a Windows Server Core 2008 R2 installation in a VMware virtual machine before setting it up on a live VPS. I've gotten remote administration via MMC working on my computer (a PC running Windows 7) for things like event logs, but I can't seem to get the firewall administration working. No matter what I do, I get the following error mesage:

You do not have the correct permissions to open the Windows Firewall with Advanced Security console. You must be a member of the Administrators group or the Network Operators group to perform this task. For more information, contact you system administrator. Error code: 0x5.

I've used cmdkey to add valid server credentials on my computer, and enabled remote management with the following commands:

netsh advfirewall firewall set rule group="remote administration" new enable=yes
netsh advfirewall firewall set rule group="windows firewall remote management" new enable=yes
netsh advfirewall set currentprofile settings remotemanagement enable

I am not running on a domain (just a workgroup), this is the only Windows Server 2008 computer I have. I've tried turning off the firewall completely, but remote administration is still failing

How do I debug this issue? Does anyone know how to fix it?

I found a few forum topics about it (eg. Remotely managing Windows Firewall on Server Core gives access denied (error 0x5) on Windows Server TechCenter) but they didn't help (I've already tried most of the fixes listed).