Microsoft Office updates fail to install

Office updates fail to install on client computers. After further investigation, it is discovered that the update returned one (or more) of the following error codes:
1603
1612
-1073741510
-2147467259
1605
Cause
There could be several reasons why these error codes are returned.
The install program for the Office* update program has the Starting Window set to Normal. This causes a command prompt window to appear on the screen and, if a user is not logged on, the update will fail.
The Office update requires access to the source installation files, but cannot find a valid path to where they are stored. Typically, Office installations come from a network share. If these files are moved, or if the path to them changes, the clients become out of date and hold an invalid location in their registry. When the update cannot find these files, it will try to prompt the user for a valid location. Since the update is set to run hidden, the window is supressed and the update fails.
It is possible for the clients to have a valid network location for source files, but when the updates attempts to retrieve those files, the update again fails. This would be caused by running the Office update with the System Account and storing the files on a share with limited access.
If you are using Notification Server 6.0 SP2, then you could be running into a known issue. The Altiris Agent was known to spawn instances of update.exe to install patches, but then did not kill them once the patch was installed. When the next patch goes to install, it will fail because update.exe is already running.
Resolution
Ensure that the update is set to run hidden, see article 23997, "How do I ensure that an Office update will run silently?"
Verify that all clients have a valid path to source installation files. See article 24002, "How do I verify that clients have a valid Office source installation files location?"
Set this update to run using different credentials. See article 22705, "Can I specify an alternate account with which to install updates?"
Apply Hotfix 20 for NS 6.0 SP2 (or just apply SP3). See article 21167, "Patches fail to install with a 1603 error code."
Hint: If the location of the Office Source Install files in article 24002 is on a Network Share, the Update needs to be run with User Credentials that has Network rights. To make this change see article 22705 for how to set up the Bulletins to be installed with a Domain User account. (Verify that this Domain User has rights to the Network share.)Note: It is recommended that the latest version of Windows Installer be installed on client computers. Older versions are known to be a catalyst for the above issues