I saw the message bellow few months ago:
Cannot connect to WMI provider.You do not have permission or the server is unreachable. Note that you can only manage SQL Server 2005 servers with SQL Server Configuration Manager.
The best solution is installing service pack 3. But if like me do not access sp3, go to bellow path via command line:
C:\Program Files\Microsoft SQL Server\90\Shared
then run this command: mofcomp “C:\Program Files\Microsoft SQL Server\90\Shared\sqlmgmproviderxpsp2up.mof”