WMI : The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

I have a vb.net 2005 program using .net framework 2.0 management classes, which loops through every computer on the local LAN and pulls back some WMI information.

When I run it from one particular Windows 2003 server, it fails on every computer with this message:

   The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

I can run the program from any other computer and it runs fine. Even another win 2003 server with the same standalone domainless configuration.

1. All computers have windows firewall turned off
2. All computers have RPC and DCOM enabled
3. All computers have the same administrator password and thats what the 2003 server is using.
4. I CAN connect to WMI on any computer from the server, using Computer Management, WMI Control, and I can connect to every c$ using windows explorer
5. None of the computers are on simple file sharing or have forceguest switched on
6. All of the computers will work when the program is run from another server, but when the 2003 server runs the program, it only works for itself. The program does not specify credentials.
7. All the computers are fully patched

WMI logs contain the following

wbemcore.log:

GetUserDefaultLCID failed, restorting to system verion(Fri Oct 05 16:30:31 2007.1529406) : GetUserDefaultLCID failed, restorting to system verion(Fri Oct 05 16:30:31 2007.1529437) : GetUserDefaultLCID failed, restorting to system verion(Fri Oct 05 16:30:35 2007.1533328) : GetUserDefaultLCID failed, restorting to system verion(Fri Oct 05 16:30:35 2007.1533578) : GetUserDefaultLCID failed, restorting to system verion(Fri Oct 05 16:30:38 2007.1535718) : GetUserDefaultLCID failed, restorting to system verion

wbemprox.log:

(Fri Oct 05 16:30:31 2007.1529421) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:31 2007.1529421) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:31 2007.1529421) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:31 2007.1529453) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:31 2007.1529468) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:31 2007.1529578) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:43 2007.1540734) : SetClientIdentity failed hr = 0x800706ba
(Fri Oct 05 16:30:43 2007.1540765) : ConnectViaDCOM, CoCreateInstanceEx resulted in hr = 0x80070005
(Fri Oct 05 16:30:46 2007.1544406) : SetClientIdentity failed hr = 0x800706ba

Framework.log

Shell Name Explorer.exe in Registry not found in process list. 10/05/2007 16:30:38.109 thread:1888 [d:\nt\admin\wmi\wbem\providers\win32provider\common\implogonuser.cpp.1019]
Unable to locate Shell Process, Impersonation failed. 10/05/2007 16:30:38.109 thread:1888 [d:\nt\admin\wmi\wbem\providers\win32provider\common\implogonuser.cpp.1027]