Dealing with STOP: C0000221 Error

Fix STOP: C0000221 Error

One of the following STOP: C0000221 error messages are displayed if a critical or any other file required to load Windows is corrupt:

"STOP: C0000221 unknown hard error

"STOP: 0xC0000221 unknown hard error
c:\winnt\system32\ntdll.dll (or other specific file/driver)"

On a Windows 2000 computer the error may read as:


How the error is displayed depends on how much of your operating system was loaded when the corrupt file was identified. Depending on this, you may receive the error on a blue screen or in a dialog box.

Cause of the Error

The error occurs because the file listed in the error message is corrupt.

Resolution Method

Depending on the severity of the problem, you may need to do one of the following tasks to resolve the error:

  • Obtain and restore a healthy copy of the corrupt file.
  • Reinstall Windows.
  • If the problem still persists, you may need to troubleshoot your system for a hardware or a network-related problem.

Registry errors and malware infections are a major cause of file corruption on a Windows system. To prevent these you must perform regular preventive maintenance with the help of reliable tools. For instance, you may repair and clean your registry with the help of a registry cleaner tool, such as RegServe, and scan and remove virus and spyware with the help of tools, such as STOPzilla Antivirus and Spyware Cease.