Regarding http://support.microsoft.com/kb/946486

Yesterday, Microsoft released an update to Windows Live Photo Gallery. I went to install it and it failed. I wasn't too worried about it since I really don't use it, but then Automatic Updates kept pestering me about it, so I figured I needed to fix it.

I looked in the event log and found the following failures:

Event Type:    Error
Event Source:    MsiInstaller
Event Category:    None
Event ID:    1024
Date:        1/23/2008
Time:        12:32:06 PM
User:        HS5\HS
Computer:    HS5
Description:
Product: Windows Live Photo Gallery - Update 'Windows Live Photo Gallery [12.0.1321.0110]' could not be installed. Error code 1603. Windows Installer can create logs to help troubleshoot issues with installing software packages. Use the following link for instructions on turning on logging support: http://go.microsoft.com/fwlink/?LinkId=23127

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 7b 32 35 37 45 34 34 30   {257E440
0008: 46 2d 37 38 31 46 2d 34   F-781F-4
0010: 35 39 42 2d 39 41 36 38   59B-9A68
0018: 2d 41 30 38 37 32 42 38   -A0872B8
0020: 30 43 31 44 36 7d 20 7b   0C1D6} {
0028: 34 43 31 45 38 46 32 44   4C1E8F2D
0030: 2d 41 39 36 39 2d 34 38   -A969-48
0038: 32 41 2d 42 42 35 31 2d   2A-BB51-
0040: 33 33 45 37 43 43 43 31   33E7CCC1
0048: 41 39 45 39 7d 20 31 36   A9E9} 16
0050: 30 33                     03     

and...

Event Type:    Error
Event Source:    MsiInstaller
Event Category:    None
Event ID:    11721
Date:        1/23/2008
Time:        12:31:44 PM
User:        HS5\HS
Computer:    HS5
Description:
Product: Windows Live Photo Gallery -- Error 1721. There is a problem with this Windows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor. Action: CA_InstallD3DX, location: C:\DOCUME~1\HS\LOCALS~1\Temp\WLXPL_DX\dxsetup.exe, command: /silent

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 7b 32 35 37 45 34 34 30   {257E440
0008: 46 2d 37 38 31 46 2d 34   F-781F-4
0010: 35 39 42 2d 39 41 36 38   59B-9A68
0018: 2d 41 30 38 37 32 42 38   -A0872B8
0020: 30 43 31 44 36 7d         0C1D6} 

Apparently the update was relying on being able to reexec DirectX setup from the temp directory install. Well, I clean my temp directories, so that didn't work. I simply went to download.microsoft.com, searched for DirectX, found the redistributable version (not the web install) downloaded it and extracted it to the directory it was expecting "C:\DOCUME~1\HS\LOCALS~1\Temp\WLXPL_DX\" in this case. I then let the update run again and it worked just fine.

Hope this helps someone.