Windows XP not letting me Log In

My friend is experiencing a weird problem with Windows XP.
Whenever he logs in, the system goes to desktop but icons & taskbar do not appear. Just as it reaches the desktop, the system shuts down on itself & bring him again at the login prompt.

The cycle repeats if one logins again. I was unable to guide him on this weird problem.
Please help as I need to fix it tomorrow at his place.

Maybe a prank... boot in safemode and check the startup list through msconfig. A simple batch file having a "shutdown -r -f -t 0" in the startup can cause this.

Not a prank, since he is the only user who uses the PC.
Can the cause be due to any virus or running harmful script? The friend has no knowledge about viruses & is an orkut addict

Orkut is full of scripts.

Yes it could be a virus problem. Download Noob Killer and do a 8-X Kill. It will clear all malware if there.

@cool G5,
Is he getting any dialog box b4 the PC shuts down, like this
*www.pchell.com/images/systemshutdown.jpg

Then its a very old worm.
Follow removal procedure here
And bookmark that site

If its not the case, then I don't know...

It can happen if the registry code for the startup of "explorer.exe" has been changed...in this case the os fails to initialise the GUI...so it again goes to the login prompt...you could try adding manually in the regedit...its the userinit key...oops...you are unable to login...oh....then you have to repair xp...it will work then...

Let me try. I am going to his house today in the afternoon.

S

just reinstall the friggin OS ... its the simplest way thou the shutdown idea seems pretty decent...

Krazy Bluez said:
It can happen if the registry code for the startup of "explorer.exe" has been changed...in this case the os fails to initialise the GUI...so it again goes to the login prompt...you could try adding manually in the regedit...its the userinit key...oops...you are unable to login...oh....then you have to repair xp...it will work then...

Right. He may be missing the userinit.exe in the registry. I faced this problem once....and you could solve this without reinstalling. But its a tedious task and I lost the link to the tutorial from where I followed.
This is another link to fix this problem. Check if it works for you and update here.

Thanks blueshift, but could not read your link as I already left early due to some other appointments.

Tried virus scanning, checking startup entries, restoring system to earlier restore point, tried repairing the system & then finally reinstalled XP as he too alongwith me were short on time.

Thanks for the responses guys.