Microsoft KB Archive/934198

= A floating-point calculation error may occur when you put the computer on standby and then you resume the computer while the calculation is in progress in Windows XP Professional x64 Edition =

Article ID: 934198

Article Last Modified on 4/24/2007

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APPLIES TO


 * Microsoft Windows XP Professional x64 Edition

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SYMPTOMS
Consider the following scenario. A Microsoft Windows XP Professional x64 Edition-based computer is running a program that is performing intense floating-point calculations. You put this computer into standby. In this scenario, a calculation error may occur when you resume the computer from standby.

Note Standby is also known as sleep mode or S3 mode. Typically, you can put a computer into standby by using one of the following methods:
 * Click Start, click Shutdown, and then click Standby.
 * Press the power button or the standby button on the computer.



CAUSE
This problem occurs because Windows XP Professional x64 Edition does not correctly maintain the state of the floating-point unit of the processor (CPU) during a standby and resume cycle.



STATUS
Microsoft is researching this problem and will post more information in this article when the information becomes available.



WORKAROUND
To work around this problem, we recommend that you avoid manually putting a computer into standby when it is running a program that performs intense floating-point calculations.

We recommend that you consider disabling the standby feature if the following are true:
 * Your organization has Windows XP professional x64 Edition-based computers.
 * The computers run programs that perform intense floating-point calculations.

To disable this feature, use a Group Policy object (GPO).



MORE INFORMATION
The x64-based versions of Windows Server 2003 and of Windows XP Professional x64 Edition are based on the Windows Server 2003 code tree. Service and support activities for Windows XP Professional x64 Edition use the Windows Server 2003 code tree. Service and support activities do not use the Windows XP client code tree. For more information about the x64-based versions of Windows Server 2003 and of Windows XP Professional x64 Edition, click the following article number to view the article in the Microsoft Knowledge Base:

888733 A description of the x64-based versions of Windows Server 2003 and of Windows XP Professional x64 Edition

Technical support for x64-based versions of Microsoft Windows
If your hardware came with a Microsoft Windows x64 edition already installed, your hardware manufacturer provides technical support and assistance for the Windows x64 edition. In this case, your hardware manufacturer provides support because a Windows x64 edition was included with your hardware. Your hardware manufacturer might have customized the Windows x64 edition installation by using unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with a Windows x64 edition. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware. If you purchased a Windows x64 edition such as a Microsoft Windows Server 2003 x64 edition separately, contact Microsoft for technical support.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site:

http://www.microsoft.com/windowsxp/64bit/default.mspx

For product information about x64-based versions of Microsoft Windows Server 2003, visit the following Microsoft Web site:

http://www.microsoft.com/windowsserver2003/64bit/x64/default.mspx

Additional query words: Winx64 Windowsx64 64bit 64-bit

Keywords: kbqfe kbprb kbexpertiseinter KB934198

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