So I naturally tried to access Win32_ComputerSystem WMI class using a Wbemtest but I was getting an Invalid class error

This looked like a corrupt WMI repository.
use CMD to run command
net stop winmgmt
select Yes or Y
sc config winmgmt start= disabled
cd %windir%\system32\wbem
for /f %s in (‘dir /b *.dll’) do regsvr32 /s %s
for /f %s in (‘dir /b *.mof’) do mofcomp %s
wmiprvse /regserver
sc config winmgmt start= auto

give it a few minutes to complete then restart server.

VBS script can also be used this cover the entire C:\ drive

Create a RebuildWMI.vbs file then copy and paste the following script give it a good 15 minutes.

set osh = createobject(“wscript.shell”)
set fso = createobject(“scripting.filesystemobject”)

ret = osh.run(“sc stop iphlpsvc”,0,true)
ret = osh.run(“sc config winmgmt start= disabled”)
ret = osh.run(“sc stop winmgmt”,0,true)

bp = osh.popup(“Service stop returned ” & ret & “. Continue?” & vbcrlf & vbcrlf & “Ensure that WMI has stopped before continuing”,,”Continue?”,33)
if bp <> 1 then wscript.quit

if fso.folderexists(“c:\windows\system32\wbem\repository.old”) then
fso.deletefolder(“c:\windows\system32\wbem\repository.old”)
end if

if fso.folderexists(“c:\windows\system32\wbem\repository”) then
set rfol = fso.getfolder(“c:\windows\system32\wbem\repository”)
rfol.name = “repository.old”
end if

set rfol = fso.getfolder(“c:\windows\system32\wbem”)

for each fil in rfol.files
if right(lcase(fil.name),4) = “.dll” then
osh.run “regsvr32 /s “”” & fil.path & “”””,0,true
end if
next

ret = osh.run(“sc config winmgmt start= auto”)
ret = osh.run(“sc start winmgmt”,0,true)

bp = osh.popup(“Service start returned ” & ret & “. Continue?” & vbcrlf & vbcrlf & “Ensure that WMI has started before continuing”,,”Continue?”,33)
if bp <> 1 then wscript.quit

set rfol = fso.getfolder(“c:\”)

recur rfol

Msgbox “WMI rebuild complete. Reboot server”

sub recur(fol)
on error resume next
if lcase(fol.name) <> “system volume information” and lcase(fol.name) <> “recycler” and lcase(fol.name) <> “boot” and lcase(fol.name) <> “$recycle.bin” then
for each fil in fol.files
if right(lcase(fil.name),4) = “.mof” or right(lcase(fil.name),4) = “.mfl” then
osh.run “mofcomp “”” & fil.path & “”””,1,true
end if
next
for each sfol in fol.subfolders
recur sfol
next
end if
end sub
Run the script at every prompt give a good 15 minutes before it completes the process

have a look at windowsupdate.log file again and it should be sweet with no errors