Rank: Guru
Rating: 85%, 145 votes
Seems that adware ,spyware or a virus caused this.
I found a solution that could work from this forum :
http://www.geekstogo.com/forum/Windows-XP-Logs-Then-Immediately-Logs-Off-t15771.html
It's an advanced technique and you will need your Windows XP setup CD.
Boot using your winxp cd.
Enter recovery console.(press R on first screen)
at the command prompt go to
C:/windows/system32
next type:
Dir *.exe
If you find, it, type
copy userinit.exe wsaupdater.exe
Exit and reboot normally. You should now be able to logon.
Run regedit
Navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\
In the right pane, you should see
C:\WINDOWS\System32\wsaupdater.exe,
Change it so that it reads:
C:\WINDOWS\System32\userinit.exe
That should solve the problem