How to fix Lsass EXE Error

So, you were working or gaming on your PC and suddenly started getting the dreaded Lsass.exe application error, which looks more or less like this:

This system is shutting down. Please save all work in progress and log off. Any unsaved changes will be lost. This shutdown was initiated by NT AUTHORITYSYSTEM

The system process 'C:WindowsSystem32lsass.exe' terminated unexpectedly with status code 128. The system will now shut down and restart.

Looks scary, doesn't it? No worries, this error might be easier to fix than you think. Since lsass errors are usually caused by a computer virus or another malware, it's a good idea to start by updating your antivirus, or downloading one if you aren't using any. To give you more time on your PC before it restarts than those meager 60 seconds, do the following:

Right click on your My Computer icon and choose Properties > the Advanced tab > click "Startup and Recovery" Settings button, and uncheck the mark saying "Automatically restart". Now your computer will not reboot even on critical errors. That of course merely gives you more time to research and solve the problem.

lsass.exe stands for Local Security Authentication Server, and is a critical component of several Microsoft Windwos operating systems such as Windows XP. That's why it's often a target of malicious software. Now that we've got more time, do the following:

1) Download and install a free antivirus program, such as AVG, Comodo or Avira - there are plenty to choose from, and most can remove viruses which cause the lsass.exe error. If you already have an antivirus on your PC, update it so it has the newest virus definitions.

2) Restart your PC and boot up in the Safe Mode. To do this, repeatedly press F8 while booting until you get the boot choice screen. Choose to boot in Safe Mode (networking isn't necessary in this case). Safe Mode makes it so only the bare bone version of your OS is boot up. Now scan your entire PC with the antivirus program.

3) Restart the PC and boot normally. Launch Windows Update and download all the upgrades needed for your OS. In most cases, lsass.exe errors are caused by malware which uses vulnerabilities in older Windows versions. As soon as you get the newest updates, your PC will be safe once more.

If the above fails, that could mean several things. First of all, your operating system files might be damaged and corrupted by said virus. Alternatively, the problem might have been caused not by malware, but by conflicting software or hardware faults in your system. That leaves you a single course of action, namely repairing your Windows installation. To achieve this, do the following:

Insert the Windows CD or DVD into your drive. Reboot the PC, and make sure your CD-ROM is set as the first boot device in BIOS. Proceed to Windows Setup and press Enter when prompted to setup Windows XP (or other) now. Press F8 to accept the terms, and once inside select your Windows installation and press R to continue.

Note that repairing your windows installation means you will lose your old registry (most installed programs won't work) and system restore points, so this should only be used as the last resort against the lsass.exe error. Do not forget to update your Windows right after repairing the installation!