Have you tried without the %comspec%?

It's always best to build the shell statement so that you can "see" what it is doing...

 Code:
$cmd="C:\Program Files\Microsoft Dynamics CRM\Client\ConfigWizard\Microsoft.Crm.Application.Outlook.ConfigWizard.exe" /q/ i "C:\Program Files\Microsoft Dynamics CRM\Default_Client_Config.xml"

? $cmd
;Shell $cmd
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(... better days ahead)