WMI 0x80041013 "Provider load failure"

A number of programs are failing with this error eg, MSinfo32, AS SSD, Samsung Magician etc. I have tried all the following actions to no avail:

1. Repaired W7 Ultimate SP1 OS using the Upgrade option with a W7 Ultimate SP1 cd.
2. Run SFC /Scannow - no errors.
3. Checked that the WMI service is running - ok.
4. Re-registered all the dll's in c:\windows\system32\wbem.
5. Re-compiled all the mof and mfl files in c:\windows\system32\wbem.
6. Ran WMIDiag.vbs. The report highlighted some 40 (WBEM_E_NOT_FOUND) errors - no different to the report from another W7 ultimate machine where WMI works ok.
7. Registered the system.management.instrumentation.dll with: "regasm %systemdrive%\program files\reference assemblies\microsoft\framework\v3.5\system.management.instrumentation.dll".
8. Rebuilt the Repository numerous times.
9. SystemInfo in CMD works fine and returns all system data ok. Msinfo32.exe doesn't.

10. Interestingly, the following script returns the correct info:

    *strComputer = "." Set objWMIService = GetObject("winmgmts:\" & strComputer & "\root\cimv2") Set colItems = objWMIService.ExecQuery("Select * from Win32_operatingsystem") For Each objItem In colItems Wscript.Echo "Name: " & objItem.Name Next*

but the same query doesn't work in Paessler WMITest.exe - where I get the same 0x80041013 error! So it seems WMI itself is working normally but not when called from, say, MSinfo32.

No WMI error in Event Viewer for startup.

Any ideas of where to go from here?

Andrew