Vista gets stuck after login

>I have temporarily solved this problem, but I'd like to know if someone can
>tell me what's happening exactly.
>
>My laptop was working ok, and from one day to other it got stuck after
>login. I was able to login, everything started ok; but after a few minutes it
>got stuck. I was able to move the mouse, but every program I tried to touch
>got stuck.
>If I try to use CTRL+ALT+SUPR to launch the taskmanager, a black screen
>appears and, after a while, it prompts a message saying something like "the
>administrative tools cannot be opened". I tried to launch the taskmanager as
>soon as I login and it works but, after a while, it gets stuck too! In safe
>mode it starts correctly, but no one of the repair tools repairs anything.
>
>I used msconfig.exe to select the services to be load. By doing a "binary
>search" I was able to find the service which was causing the problem:
>searchindexer ("Busqueda de Windows" in Spanish). I disabled it, and now I
>can use my laptop without problems.
>
>The point is that one day it was working and the next day it suddenly fails.
>I hadn't installed any new software and my hardware configuration didn't
>change... so why?