Winlogon.exe error. Windows XP won't load, even in Safe Mode.

This is windows xp system. Somehow it got effected with malware last weeks. Since then I kept my system turned off. Yesterday in order to clean the system I ran Webroot Spysweeper which detected the following malwares Haxdoor, TIBS Dialer, CoolWebSearch, and Instant Access. Webroot Spysweeper attempted to remove these items and later it gave a pop saying me to restart the system. I did the same restarted. When it was restarting, I got the following error message:

SAS Window: Winlogon.exe -- Application Error
The instruction at "0x77f581bd" referenced memory at "0x0070803c". The memory could not be "written." Click on "ok" to terminate the program.

There was an OK button. When I clicked on the same system restarted again and got stuck at the same message. From here the process is repeating on clicking OK. I don’t have any idea what to do now. Somebody please help.

Thank you.

getting malware or virus is never good. No matter what we do to clean, they use to leave their traces on the system which creates problems. Anyways, here is what you need to go through in order to fix the restarting problem:

Boot the system using the Windows XP CD-ROM. In the first screen when the Setup begins, read the instructions press "R" (in the first screen) enter the Recovery Console. Type-in the built-in Administrator password to enter the Console. You'll see the prompt reading C:\Windows (Or any other drive-letter where you've installed XP)

Type the following command and press Enter.
CD SYSTEM32
(If that does not work, try CHDIR SYSTEM32)

COPY USERINIT.EXE WSAUPDATER.EXE

Quit Recovery Console by typing EXIT and restart Windows.You'll be able to login successfully as you've created the wsaupdater.exe file (now, a copy of userinit.exe) Now, change the USERINIT value in the registry (see Phase II in this page) and change it accordingly.