Microsoft KB Archive/252500

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Ntbackup.exe May Cause 100 Percent Central Processing Unit Utilization

Article ID: 252500

Article Last Modified on 2/20/2007


  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Exchange 2000 Server Standard Edition

This article was previously published under Q252500


If you use Windows 2000 Backup (Ntbackup.exe) to schedule a backup on your Windows 2000-based computer running Exchange Server version 5.5, when the backup process starts, the backup tape is not overwritten, and you may receive the following error message:

There is no unused media with the selected type. Add unused media or click cancel to select another type.

Also, after you quit Ntbackup.exe, you may experience one or more of the following symptoms:

  • The central processing unit (CPU) registers 100 percent utilization, but no process lists high CPU utilization.
  • Ntbackup.exe is still listed in the running processes list in Task Manager, however, it is not visible on the desktop.
  • Your computer may stop accepting connections, and Messaging Application Programming Interface (MAPI) clients may time out.
  • Your computer is very slow to respond to input, and you may experience a 10 to 20 second response delay when you ping your loopback adapter.


To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

NOTE: To view the file version, right-click Ntbackup.exe in Windows Explorer, click Properties, and then click the Version tab.

The following files are available for download from the Microsoft Download Center:

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.
To work around this problem, stop the Ntbackup.exe process in Task Manager.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 1.

Keywords: kbhotfixserver kbqfe kbdownload kbbug kberrmsg kbfix kbgraphxlinkcritical kbqfe kbwin2000sp1fix KB252500