According to Microsoft, error 1625 means "This installation is forbidden by system policy. Contact your system administrator."
Like most Windows Installer errors the problem is not with the delivery mechanism (PDQ Deploy in this case) but with the environment. In this case the installation of Flash Player has been blocked by Group Policy. In order to install or deploy Flash Player the system policy must be modified.
Error : MSI failed with error code 1625
Error Type : AdminArsenal.PDQDeploy.MsiOtherException
License Mode : Free
Memory : 12 GB (10 GB free)
Product : PDQ Deploy
Subject : PDQ Deploy Diagnose Report
Version : 126.96.36.1990
Windows : Microsoft Windows 7 Professional (6.1.7601.65536)
MSI failed with error code 1625
File Path: C:\Users\Public\Documents\Admin Arsenal\PDQ Deploy\Repository\Adobe\FlashPlayer\install_flash_player_11_active_x.msi
MSI Error Code: 1625
Command Line: msiexec.exe /i "install_flash_player_11_active_x.msi" ALLUSERS=1 /q /norestart