Ok, The problem that I am having has been (sorta) resolved. It is actually a bug with how the Installer executes and installs itself. The issue lies in the fact that Office 2007 installed straight through the MSI at the first install of Windows (through Group Policy) has to compete with other products that are also installed at this stage (i.e. Acrobat, Windows Defender, Zune Theme and so on). The Problem is two-pronged and is as follows (with the workaround below, different colour) 1. Installing Software which auto-reboots the system after installation (Adobe Acrobat 8, in my case) If your Machine's installers are set to reboot the machine after they are installed, Office 2007 will not be correctly configured or installed, as the Office 2007 installation runs as a 'All Users' account at the logon prompt and then on top of the interactive logon and restarting the machine naturally prevents this from executing (and the Office 2007 MSI IS NOT self-healing. Solution: The Office 2007 installer MUST be run AFTER all other installers for it to correctly function, as it does not call a restart (i.e. if you are creating a new Software Installation GPO, be sure to add Office 2007 last 2. Installing Software which runs after the logon (such as the Zune Theme asking to be set, or Windows Defender running a scan) When software installs normally (as the logged on user), it may call a window, such as the Zune theme asking to be set or Windows Defender running an update and scan. When software is installed from Group Policy, these windows or applications are called at the First Interactive logon. It happens that the installer for Office 2007 also wants to be executed here as well, but will fail if any other applications are already running (such as these called windows.) As a result, the installer will show that another 'installation' is in progress, becasuse applications/windows have been called by the other installers- another installation in the eyes of Office 2007, and will 'Roll-Back' changes, and ask for you to press 'Retry' after the install (which does not show). Because the Office 2007 MSI installer is not self-healing, the subsequent restart will not recognise any problem and Office 2007 cannot be installed. Each program (e.g. Word 2007) will show in Add/Remove as "Word 2007 MUI en-us" but will not be in C:\Program Files\office12\winword.exe. Solution: Installers which call an application after installation CANNOT be installed using Group Policy if Office 2007 is to be installed. Essentially what it boils down to is a sloppy MS Engineer who didn't test Office 2007 installing with other applications at the first system install, rather only as an additional install to an existing GPO and existing computers, not new, GP installed computers. The only way around this problem is to use BDD 2007, and even then some of these programs will not install correctly (such as PowerDVD) which check for other installed software (e.g. DirectX) which they will not find in Windows PE.