I found a different MS Article (555294) with almost the same info. The only difference is this article indicates that a trailing comma (,) is reqired for the value in the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit key.
Like this: C:\WINDOWS\system32\userinit.exe,
I don't know if the comma was overlooked in the 899865 article, or if the entry was changed in SP2. I don't think so as I have SP3 installed and the comma is still there on my system.
Might be worth a try...