Malware

Try this

Enter the Recovery Console

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)
At the prompt type in
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)

"WARNING MODIFYING REGISTRY INFORMATION IS DANGEROUS"
Backup the Key before making changes.

Now, change the USERINIT value in the registry
Click Start, Run and type REGEDIT. Navigate to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon

In the right pane you will see that the value of the Userinit key is incorrectly set to "wsaupdater.exe,"


In the right-pane, change the value of Userinit to C:\WINDOWS\system32\userinit.exe,

Type the above value exactly as given, including the comma. Also, change the path to userinit.exe appropriately if Windows is installed in a different drive.

Close Registry Editor and restart Windows.