I probably shouldn't kick this topic, but I will do it anyway. ;-) I'm having the same problem as described above. I try to run an MSI from Adobe Reader from an UNC path with file rights assigned to an eDirectory group. The bundle has "Run as secure system user" as secure level. The following error appears in my zmd-messages.log:

[DEBUG] [11/12/2009 08:31:34.687] [1244] [ZenworksWindowsService] [25] [] [ZenCommon] [] [Failed to find sid in local accounts. Looking in AD accounts] [] []
[ERROR] [11/12/2009 08:31:34.953] [1244] [ZenworksWindowsService] [25] [Testpda] [BundleManager] [WindowsActions.MSI_ERR_1620] [Error installing AcroRead.msi. This installation package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer package.] [] [fe57d5f18d83006ab3f55d4b5d8f1f49]
Is there any solution for this problem? Thanks!