Failed to initialize all WMI classes

Suddenly all WMI related functions don't work anymore.

When I go to Computer Management > Services and Application > WMI Control
and then ask for the properties of this WMI Control I get the message:
Failed to initialize all required WMI classes.
Win32_Processor: Win32: Access denied
Win32_WMISetting: Successfull
Security information: Successful
Win32_operatingSystem: Win32: Access Dienied

Anyone an idea who to fix this problem?

Kind Regards,

Arthur Kater
PlazaLOGIC

p.s. Using Google I found tons of people with this problem, but no-one with
a solution...