c:\windows\system32\lsass.exe
[B]WinTasks Process Library[/B]
lsass - lsass.exe - Process Information
Process File: lsass or lsass.exe
Process Name: Local Security Authority Service
Description: Windows Local Security Authority Server Process handles Windows security mechanisms. It verifies the validity of user logons to your computer or server. Technically, the software generates the process that is responsible for authenticating users for the Winlogon service.
Company: Microsoft Corp.
System Process: Yes
Security Risk ( Virus/Trojan/Worm/Adware/Spyware ): No
Common Errors: N/A
You cannot end this process from Task Manager. This is the local security authentication server, and it generates the process responsible for authenticating users for the Winlogon service. This process is performed by using authentication packages such as the default [B]Msgina.dll[/B]. If authentication is successful, Lsass generates the user's access token, which is used to launch the initial shell. Other processes that the user initiates inherit this token.
I would verify that these two files, LSASS.EXE and Msgina.dll, are in your I386\sytem32 folder.