System May Become Unresponsive When Using a Modem

Support for Windows XP has ended

Microsoft ended support for Windows XP on April 8, 2014. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

This article has been archived. It is offered "as is" and will no longer be updated.

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
When you are using a notebook computer that employs the Intel 440MX chipset and an AC'97 soft modem, you may experience the following symptom with Windows XP:
  • When you use the internal modem on the notebook computer, Windows XP may seem to stop responding (hang).
This problem has been confirmed to occur only on computers using the Intel 440MX chipset and an AC'97 soft modem. These computers require an updated system BIOS and an updated driver file (P3.sys) so that Windows XP can fully support the Intel SpeedStep Technology power-saving functionality concurrent with modem operations. As of November 2001, this configuration is typically found on only a small range of sub-compact laptop computers using the Intel 440MX chipset in support of the Mobile Intel Pentium III processor-M CPU.
To resolve this problem, obtain the latest service pack for Windows XP. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
322389 How to Obtain the Latest Windows XP Service Pack
There are three steps needed to correct this issue:
  1. Obtain an updated BIOS from your notebook computer manufacturer. For information about how to update the BIOS, please contact your notebook computer manufacturer.
  2. Apply the update below.
  3. Update the registry per the "Enabling the New Driver to Use SpeedStep Technology" instructions below.
This update is available on the Microsoft Windows Update Web site.The English version of this fix should have the following file attributes or later:
   Date         Time   Version      Size    File name   --------------------------------------------------   29-Aug-2001  15:57  5.1.2600.10  37,248  P3.sys   29-Aug-2001  16:20                1,521  P3qfe.inf				

Enabling the New Driver to Use SpeedStep Technology

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

After you install the fix from the Microsoft Windows Update Web site, you must make the following registry change:
  1. Start Registry Editor (Regedit.exe).
  2. Locate and click the following key in the registry:
    You may have to create the Parameters key if it is not already present.

  3. On the Edit menu, click Add Value, and then add the following registry value:
    Value name: HackFlags
    Data type: REG_DWORD
    Radix: Hexadecimal
    Value data: 1
  4. Quit Registry Editor.
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 XP Service Pack 1.
Intel 440 MX Errata #34

Article ID: 306580 - Last Review: 01/11/2015 20:54:15 - Revision: 2.0

Microsoft Windows XP Home Edition, Microsoft Windows XP Professional

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