The above old post helped me fix a problem that I ran into, but I have a couple things to add that I ran into which weren't in the original above post.
After removing some malware with Malwarebytes and uninstalling Windows Search, after reboot, you could log into any local account in XP, but you'd momentarily see the wallpaper then it would log you right back out. So I tried the first step in the above article, I made sure there was a userinit.exe and wsaupdate.exe in the C:\Windows\System32 folder, but it still didn't work.
What I did then was boot up with a Winternals CD and accessed the registry on the hard drive. I found out that the the entire string value [Userinit REG_SZ C:\Windows\System32\userinit.exe] was missing from the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\ registry key. So I had to create a new string value and enter in the correct information.
Hope it helps anyone with the same problem.
Assume that I already did an Internet search.