When you run Virtual PC 2004 on a portable computer that uses the Intel Centrino 915 chipset, Virtual PC performance is reduced

When you run Microsoft Virtual PC 2004 on a portable computer that uses the Intel Centrino 915 chipset, Virtual PC performance is reduced when compared to its performance on portable computers that use older Centrino chipsets.

The Centrino 915 chipset has a new power saving architecture that disables the Time Stamp Counter (TSC) when the chipset uses the Intel SpeedStep technology. This behavior causes Virtual PC 2004 to make incorrect calculations.

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. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

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, contact 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.

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Hotfix installation instructions

Select a hotfix file based on the following rules:

• If you have installed Virtual PC 2004 and then upgraded the installation to Virtual PC 2004 Service Pack 1 (SP1), use the Vpc2004qfe899525_update.msp file to install this hotfix.
• If you have installed Virtual PC 2004 with SP1, use the Vpc2004qfe899525_msdn.msp file to install this hotfix.

To apply this hotfix, follow these steps:

1. Run the appropriate .msp file for the Virtual PC 2004 installation type.
2. Move to the %root%\Documents and Settings\%username%\Application Data\Microsoft\Virtual PC folder.
3. Right-click the Options.xml file, and then click Edit.
4. Add the following code to the file.

   	<virtual_machines>
         		<enable_idle_thread type="boolean">true</enable_idle_thread>
   	</virtual_machines>

   
   Note The <virtual_machines> tags should be at the same level in the code as the <virtual_network> and <virtual_gateway> tags.

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

For more information, click the following article number to view the article in the Microsoft Knowledge Base: The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.