I'm not sure if this is related to the installation of Service Pack 3 on this XP box or not, but I recently ran into the following error after running "Add/Remove Windows Components" from within "Add/Remove Programs."
For those unable to see the above image, it says, "Setup was unable to open information file msnmsn.inf. Contact your system administrator. The specific error code is 0x2 at line 0."
Then you click okay and you get the following dialog.
"The application could not be initialized." Ahh, the death throws of the Windows setup application...
Well, from the error, it sure sounds like something is failing to parse an INF file. But why? This sounds like a job for ProcMon!
Sure enough, searching the ProcMon results for msnmsn.inf after running the setup again shows us the following...
File not found! Why on Earth would that suddenly go missing? No clue how this happened. But here's how you fix it. Copy the msnmsn.inf from C:\Windows\ServicePackFiles\i386 into C:\Windows\System32\Setup.
But wait! There's more! After doing this, I got a different error. This time it said it couldn't find ocmsn.dll. It turns out that C:\Windows\ServicePackFiles\i386 has a copy of ocmsn.dll as well, so I copied it to C:\Windows\System32\Setup.