Can't access Config Mgr. Cannot connect to WMI provider. You do not have permission or the server is unreachable SQL 2005

Hi, I'm getting the below message when i try and access SQL Config Manager on my Windows Server 2003 box running SQL Server 2005 SP3.

"Cannot connect to WMI provider. You do not have permission or the server is unreachable. Note that you can only manage SQL Server 2005 and later servers with SQL Server Configuration Manager.
Invalid namespace [0x8004100e]"

I've looked at lots of forums and most suggest running mofcomp below but this does not work, there is no sqlmgmprovider*.mof file anywhere in the machine:

C:\Program Files\Microsoft SQL Server\90\Shared>mofcomp "C:\Program Files\Microsoft SQL Server\90\Shared\sqlmgmproviderxpsp2up.mof" or sqlmgmprovider.mof

I can see all the databases in SQL Server Management Studio ok and can connect.

I'm stumped !! I'm a SQL novice, any help greatly appreciated. One thing i'll mention is the C:  drive did run out of space, but whwther that's got anything to do with it?