Windows XP SP2 Laptop Battery Drain patch (KB918005)

Microsoft heeft gisteren eindelijk een patch uitgebracht voor een probleem waar wij eerder in februari al melding van maakten. Er zit namelijk een probleem in de USB- en de ACPI-functionaliteit van Windows XP Service Pack 2. Deze fout zorgt ervoor dat accu's tot 30 procent sneller dan normaal leeglopen wanneer een USB-apparaat is verbonden met een laptop. Nu is er dan eindelijk hotfix nummer KB918005 die dit op moet lossen. Meer informatie over deze hotfix is op deze pagina te vinden, hier volgt tenslotte nog even een uitgebreide omschrijving van het probleem:

SYMPTOMS

• When you unplug the AC power from a Microsoft Windows XP-based portable computer, the battery may drain more quickly than you expect. Therefore, the operating system may shut down prematurely.

CAUSE

This problem may occur if one of the following conditions is true:
• The portable computer cannot enter the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states.
  This occurs when the USB 2.0 driver leaves the asynchronous scheduler component running continuously. This prevents the processor from entering the deeper ACPI processor idle sleep states, or C-states. C-states save power when the processor is not busy. These states range from C0 to C3 or C4. Typically, an idle portable computer uses the C3 and C4 states to preserve battery power. If an idle portable computer cannot enter or maintain the C3 or C4 states, the battery power drains more quickly. This problem is fixed by installing the download that is available in this article.
• The USB host controller is unable to turn off.
  This typically occurs when devices are removed from a nested USB hub that is attached to the host controller. The host controller does not recognize the device removal. Therefore, the controller is never turned off. This prevents the processor from entering the ACPI processor idle sleep states. This problem is not fixed by installing the download that is available in this article.
• The USB host controller uses the periodic scheduler for USB 2.0 devices.
  This typically occurs when devices that rely on the periodic scheduler are attached to the host controller. These may be isochronous (Isoch) devices such as audio devices. Alternatively, they may be interrupt devices such as mouse or keyboard. This problem is not fixed by installing the download that is available in this article.