System shutting down

This is a security flaw in Microsoft Windows, mainly NT/XP/Server.
If you see this message you should install Windows updates as soon as possible. There is basically someone out there sending data to your PC causing this to happen.

Advisory Warning to all users of the following operating systems:

Microsoft Windows NT 4.0
Microsoft Windows NT 4.0 Terminal Services Edition
Microsoft Windows 2000
Microsoft Windows XP
Microsoft Windows Server 2003

Your Microsoft Operating System may potentially be under attack by HACKER ACTIVITY. The vulnerability attack can fool software into accepting insecure commands that could let intruders steal data, delete files or eavesdrop on e-mails.

Due to the seriousness of this vulnerability the Department of Homeland Security and Microsoft encourages system administrators and computer owners to update vulnerable versions of Microsoft Windows operating systems as soon as possible.

Our recommendation is to please go to:

http://microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS03-026.asp to install the patch immediately.

Hi.,
There are two things to be looked into w.r.t ur messages. The NT Authority " and the "Lsass.exe" message.
1,
NT Authority is definitely the blaster worm.To remove this.. Follow these steps

Click Start->Run->Type "Services.msc" [without the quotes] and look for remote procedure call in the list. [u wud find 2 listings]. Click on the first one and click on the recovery tab. And change the options on First Failure, second failure and third failure to "Restart service".
Click apply and OK.
Now go to vil.nai.com/vil/stinger/ and download the stinger from NA to scan and remove the blaster worm. Then we need to download the security patch from microsoft. goto windowsupdate.microsoft.com and u wud find the details there.

2.
Lsass.exe
Insert the XP CD in the CD drive and boot the computer to the CD
And at the welcome to windows setup menu, press R to select recovery console.
You will be prompted for the windows installation you want to repair, press 1 then [enter]. You will receive a password prompt, press [enter]
You will then get a C:\windows\> prompt.
Change directory to the
C:\WINDOWS\SYSTEM32\DLLCACHE folder using the following command:

cd \windows\system32\dllcache [enter]

Copy the LSASS.EXE file to C:\WINDOWS\SYSTEM32 using the following command:

copy LSASS.EXE C:\WINDOWS\SYSTEM32\LSASS.EXE [enter]
Type EXIT [enter] & system will reboot.
and that wud resolve the issue.

ALL THE BEST!!