On some of my machines I noticed that I was having trouble upgrading to the latest service pack for some of the products I have installed (e.g. Visual Studio 2005, SQL Server 2005, etc.).  It wasn’t a critical problem and I didn’t have the time to spend on tracking it down at that time so I just let it go.  A friend of mine (Paul Erickson) had a more immediate need to solve it and he shared the solution.

It turns out that there is a bug in the Windows Installer.  For some reason Microsoft has not made the fix available via Windows Update, so you have to install the patch manually.  Note that this only applies to Windows Server 2003 and Windows XP Professional (at least according to the article).

Once the patch was installed and I rebooted, the service packs from Windows Update installed successfully.

I don’t typically like to do this, at least not publicly, but I’m going to do it now.

[RANT]
I find Microsoft’s Windows Update solution to be extremely useful, especially when there are no problems, but when a problem occurs, it is extremely difficult to find out what is wrong.  Maybe there are some users who don’t want to be bothered, but by withholding the error information from everyone, they make it way too difficult to troubleshoot problems.  I find that so very frustrating.
[/RANT]

Okay, there, I did it.  I feel better. :-)