InstallUpdates - System.UnauthorizedAccessException - 0x80070005

Question

Hello,
I'm running into the following problem which I'm certain isn't an issue with the SDK but checking to see if anyone else ran into this problem and found a solution.
I have a PS script to find all the updates made available to an endpoint via CM2012 and initiate the installation using the SDK.  The following two lines in the script is what I'm using and they work...most of the time.
$MissingUpdates = @(Get-WmiObject -ComputerName $ServerName -Credential $credential -Class CCM_SoftwareUpdate -Filter ComplianceState=0 -Namespace root\CCM\ClientSDK | foreach {[WMI]$_.__PATH})
Invoke-WmiMethod -ComputerName $ServerName -Credential $credential -Class CCM_SoftwareUpdatesManager -Name InstallUpdates -ArgumentList (,$MissingUpdates) -Namespace root\ccm\ClientSDK
The times where it's not working I receive a "System.UnauthorizedAccessException" error message.  Problem is after reviewing two different endpoints, one where it works and one where it doesn't work, I'm at a loss as to what could be blocking the script
to invoking the method 'InstallUpdates'. 
I'm using a domain admin account to run the script and have verified that the account is showing up in the Administrators group on the problematic endpoint.  I've also manually added the account to the Administrators group (just to be safe), within
the WMI Control (and afterwards restarted the WMI service), DCOM permissions to local/remote launch, to the WMI DCOM Application, changed the PS execution policy and used wbemtest.exe to see the error...
Number: 0x80070005
Facility: Win32
Description: Access is denied.
The error 0x80070005 lead me to check the DCOM permissions per WMI Troubleshooting article out on MSDN.
Inspite of all these checks, still can't invoke the method successfully.  Both endpoints are running Windows Server 2008 R2. 
Any insight would be appreciated.  Thanks!

Answer 1

Again thanks AGS_MN.  Just to be sure I also ran your code. 
$Namespace = "root\ccm\Policy\Machine\ActualConfig"
$Class = "CCM_ClientAgentConfig"
$Current_ClientAgentConfig = Get-WmiObject -Namespace $Namespace -Class $Class -ComputerName '<myservername>' -ErrorAction Stop
$Current_ClientAgentConfig.InstallRestriction
Set-WmiInstance -InputObject $Current_ClientAgentConfig -ErrorAction Stop
$MissingUpdates = @(Get-WmiObject -ComputerName '<myservername>' -Credential $credential -Class CCM_SoftwareUpdate -Filter ComplianceState=0 -Namespace
root\CCM\ClientSDK | foreach {[WMI]$_.__PATH})
Invoke-WmiMethod -ComputerName '<myservername>' -Credential $credential -Class CCM_SoftwareUpdatesManager -Name InstallUpdates -ArgumentList (,$MissingUpdates)
-Namespace root\ccm\ClientSDK
Only difference is the code (because of the -Credential) prompts me for username and password, but still errors the same as mine.