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Article ID: 327868 - Last Review: January 17, 2015 - Revision: 1.6

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When you connect a serial modem to a hot-plug serial interface controller (RS-232) on a Microsoft Windows 2000-based computer, the enumeration process for serial devices (Serenum.sys) may not recognize the modem.


This problem occurs when the Routing and Remote Access service tries to connect to a discovered modem while the Serenum.sys service is enumerating the COM port that is connected to the hot-plug serial interface controller. In this case, the Serenum.sys service locks the port during the enumeration process. Therefore, Routing and Remote Access cannot connect to the device.

Note Serenum.sys is the Windows 2000 filter driver that enumerates serial devices.


Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: (
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
   Date         Time   Version            Size    File name
   03-Oct-2002  17:48  5.0.2195.6078      14,160  Serenum.sys
   03-Oct-2002  17:49  5.0.2195.6078      60,880  Serial.sys
   13-Jun-2001  05:05  5.0.2195.3727       3,856  Svcpack1.dll     


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the following article number to view the article in the Microsoft Knowledge Base:
265173  ( ) The Datacenter program and Windows 2000 Datacenter Server product
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
824684  ( ) Description of the standard terminology that is used to describe Microsoft software updates

  • Microsoft Windows 2000 Advanced Server SP3
  • Microsoft Windows 2000 Service Pack 3
kbnosurvey kbarchive kbautohotfix kbhotfixserver kbqfe kbwin2000presp4fix kbbug kbfix KB327868
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