What is Ntdll.dll ? - The ntdll.dll file is a file containing NT kernel functions. Its description is "NT Layer DLL”. This file is located in c:\windows\system32 or c:\winnt\system32 directory and it can also be found in the c:\i386 directory.

Because this file is part of the OS registry you should never delete or remove this file even if it has been infected by a virus or a Trojan. The best way to fix it would be to run a virus scan.

When does this registry error occur? - Ntdll.dll error messages often appear before, during or after a program is runs. It also appears when Windows is started or shutdown. Ntdll dll unknown hard error is caused by a number of different causes. Here are a few:

• a corrupt/ damaged version of the ntdll.dll file
• corrupt hardware drivers,
• conflict between Windows and other applications.
• Disfunctional hardware.

Here are some common ntdll.dll registry errors you may come across:

• STOP: C0000221 Unknown Hard Error \SystemRoot\System32\ntdll.dll
• STOP: C0000221 unknown hard error Path\File_name
• STOP: 0xC0000221 unknown hard errorC:\Winnt\System32\Ntdll.dll (or another specific file or driver)
• STOP: 0xC0000221 STATUS_IMAGE_CHECKSUM_MISMATCHPath\File_name

How Do I solve a Ntdll.dll error ? - Many of these errors are often due to a one-time issue. In this case a simple reboot often resolves the error.

In most cases relating to a corrupt or missing NTDLL file, simply download a replacement off the internet. The most crucial issue to worry about however is to keep your registry in a good running shape. Here are a few simple tips:

• Get a registry repair tool. There are hundreds of excellent utilities on the internet.
• Maintain a good and regular registry maintainance routine.
• Have an efficient antivirus to avoid the corruption of registry files by viruses and Trojans.
• Avoid download unreliable and bad drivers