Is it Ntdll.dll or bad hardware?
Ntdll.dll files created by Microsoft are officially designated as “NT Layer DLL”.
These are the files, which contain the NT kernel functions. They can be found in the c:\windows\system32 or c:\winnt\system32 directory. When an error is encountered, you will see the following on your screen: STOP: C0000221 Unknown Hard Error/SystemRoot\System32\ntdll.dll
The ntdll.dll file that is included with the Microsoft Windows installation is not any sort of Trojan, nor is it spyware, or a virus. Nonetheless, as with any file appearing on your PC, it can become corrupted due to an encounter with a virus. Antivirus software can identify and clean files. Because this file is part of Windows, users must never remove it if they suspect that it is contaminated.
Should you encounter this error while using Microsoft IE, you can frequently resolve the matter by eradicating any third-party add-ons. Below are listed several assorted recommendations that have been identified to fix this issue.
The first issue we come to is the possible corruption of the current Windows installation. Ensure the disc you are using to set up Windows is not scratched.
If you are attempting an installation of Windows from a burned CD and you encounter this problem, it may very well be the CD is the issue. We would recommend obtaining a legitimate version of Windows.
Hardware problems reveal below could initiate issues throughout the Windows installation and spawn this error after completion of the installation.
Verify that your PC does not have an EIDE/IDE cable that is defective.
Additional devices that occupy the same EIDE/IDE cable as your hard disk drive can generate this issue also. Temporarily disconnect any of the devices on the cable and try the installation again.
Ensure you have current drivers installed for all your devices. When installing drivers validate the correct drivers of the device is being downloaded.
If you believe, any of the above issues generated your problems; we suggest re-installing Windows after correcting the associated issues.