I put together a GPO to deploy a MSI file to a security group comprised of computer objects. After rebooting a test workstation so that it picks up its group membership and running gpupdate, I then ran gpresult /r and I see that it is picking up the GPO for the software installation. After a reboot, the software does not install. Our anti-virus (SEP Cloud) blocks WMI for all workstations, which I suspect is the issue. Does anyone know if WMI is required for group policy to deploy software? If so, I will write a VBS script to do this instead.
Man, I can hardly imagine how many things in your environment must be broken if remote WMI can't be used, even from domain controllers, SCCM servers, etc. Sounds painful. But anyway,
According to this article:
http://technet.microsoft.com/en-us/library/cc782152(v=WS.10).aspx
No it doesn't rely on WMI. As long as the Group Policy client can access Sysvol, and access the software distribution point (which may or may not also be in Sysvol,) and the Windows Installer is in good working order on the client, that'll do. Also note that software deployment doesn't work over a slow link - so make sure a fast link was detected.
Edit: Also check this question for some other basic tips for troubleshooting software deployment failures:
Deploying .msi application through GPO doesn't work
Oh, and finally... try turning off your AV and see if it works then. Then you'll know if your AV is breaking it or not.