Isass.exe is a file created by Microsoft to enforce the security policy in the Windows operating system. It verifies user identification, acknowledges password modifications, and distributes access tokens. It also tracks security processes and records them to the Windows Security Log.

When the Isass.exe file authenticates user identification it will create the access token which includes a file security descriptor that completes the authentication process.

If the Isass.exe file is terminated it causes Windows Welcome to drop all of the user accounts which causes the crash on bootup. The computer is basically useless since the access token that authenticates users cannot be acquired from the server.

Rule out Malware

Malicious software can also disguise itself as an Isass.exe file and it is a worm that does not require any human activity to spread. It also does not replicate itself through electronic mail like most common worms. If you suspect your PC has been infected you can try booting up Windows and then immediately choose “Run” from the Start menu and when the Command Prompt appears, enter “shutdown –a” and then click “OK.”

If this fails to work you can access the Control Panel and click on “System.” Choose “Startup and Recovery” and then click on “Settings.” Remove the check mark from “Automatically Restart.”

This will terminate the isass.exe cycle that the computer keeps going through because it cannot locate the access token from the server. Once you finish the process you can start your PC in Safe Mode and run an anti-malware scanning program.

Solving the Isass.exe Error

There are few ways that you can solve an Isass.exe error. The first method involves using the System Restore utility. You will most likely have problems accessing Windows because it will be in the constant boot and reboot process since it is trying to locate the access token from the server. The alternative is to use your Windows disk.

• Safe Mode: Start up your PC and press F8 as you are booting up to start the computer in Safe Mode and then choose

  “Safe Mode.” Select the correct operating system and then press the “Enter” key.

• Log In: You will have to log in as administrator and when the Command Prompt appears type in

  “%systemroot%\system32\restore\rstrui.exe”

  and then tap the “Enter” key. From this point you will be walked through the process of restoring your computer to the previous state.

"Cannot Locate a Component"

If the Isass.exe error indicates that is cannot locate a component this is caused by a .dll file which has been dropped during the bootup process. To solve the error problem you will be required to use the Windows CD. Before you insert the installation disk press down the “Shift” key on your keyboard and then insert the disk. This will prevent automatic startup of Windows.

Expand the CD Drive

Choose “Run” from the Start menu and when the Command Prompt appears enter:

“expandCDdrive:\i386\ntdsapi.dl_%SystemRoot%\windows\system32\ntdsapi.dll”

and then press the “Enter” key. Take note of the drive letter for your CD drive and then enter:

“expand E:\i386\ntdsapi.dl_%SystemRoot%\windows\system32\ntdsapi.dll”

and then press the “Enter” key.

In the Command Prompt

Once you have completed this process choose “Run” from the Start menu once again and then enter “cmd” in the Command Prompt and then press the “Enter” key. When you are prompted again enter

“xcopy c:\windows\servicepackfiles\i386\ntdsapi.dll c:\windows\system32” and then press the “Enter” key.

Follow Through: Scan the Registry

Once you have solved the Isass.exe error scan the registry of your PC to search for any additional errors or corrupt files. If the registry identifies any additional files related to the Isass.exe error you can simply click on “Remove” to complete the process and place your registry back in working order.