Application Management Error Event ID 102

I ran into the following problem when deploying managed software via group policy today. I received the following error in my event logs.

Event Type: Error
Event Source: Application Management
Event Category: None
Event ID: 102
Date: 5/21/2010
Time: 12:09:05 PM
User: NT AUTHORITY\SYSTEM
Computer: CITRIX2
Description:
The install of application Microsoft Office Professional Edition 2003 from policy Terminal Services Software Installation failed. The error was : This installation is forbidden by system policy. Contact your system administrator.



This error will occur if Windows Installer is not able to run. In my case what was preventing it is I had a group policy computer setting called "Disable Microsoft Windows Installer" set to "Enabled - Always". This policy is under:

Computer Configuration --> Administrative Templates --> Windows Components --> Windows Installer

After setting this to disabled temporarily, my group policy software deployment worked.