Microsoft Releases Battery Eating Driver Fix

[GhostShip]

A worryingly long tale of foot dragging over an important aspect of laptop usage.

http://www.tgdaily.com/2006/02/14/microsoft_to_release_patch_for_power_drain_bug/

Tom's Hardware Guide worked with engineers from both Intel and Microsoft. Through our extensive collaborative research, we can report that an Advanced Configuration and Power Interface (ACPI) driver in Windows XP Service Pack 2 is the sole cause of the unusually high power drainage observed by all three teams. Today, Microsoft confirmed to TG Daily that it is developing a new patch to fix this particular driver bug, whose nature is somewhat different of those those addressed by earlier Microsoft Knowledgebase postings.

"The TG Daily article brought to our attention that our existing workaround is difficult to implement," said Michael Burk, PR manager for Microsoft's client team. "We also learned that we will need to issue a BIOS update in addition to a Registry modification, to make sure that the fix will be stable." While the existing workaround, which we reported on earlier, is somewhat efficient in regaining substantial battery time for notebooks connected to USB 2.0 devices, Burk told us this new patch will go even further to address these new issues.
A Windows XP SP2-based portable computer uses its battery power more quickly than you expect when a USB 2.0 device is connected
View products that this article applies to.

Well, thats the problem spanning 5 pages here is the solution.

Article Article ID : 899179
Last Review : July 12, 2005
Revision : 1.0
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 (https://premier.microsoft.com/kb/256986/ [microsoft.com]) Description of the Microsoft Windows registry
SYMPTOMS
Consider the following scenario. You install Microsoft Windows XP Service Pack 2 (SP2) on a portable computer. Then, you connect a USB 2.0 device to the computer. In this scenario, the computer uses its battery power more quickly than you expect.
CAUSE
Windows XP SP2 installs a USB 2.0 driver that initializes any connected USB device. However, the USB 2.0 driver leaves the asynchronous scheduler component continuously running. This problem causes continuous instances of memory access that prevent the computer from entering the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states. These processor idle sleep states are also known as C states. For example, these include the C3 and C4 states. These sleep states are designed, in part, to save battery power. If an otherwise idle portable computer cannot enter or maintain the processor idle sleep states, the computer uses its battery power more quickly than you expect.
RESOLUTION
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk. To resolve this problem, add the EnIdleEndpointSupport entry to the USB registry key. To do this, follow these steps:1. Click Start, click Run, type regedit, and then click OK.
2. Locate, and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\USB
Note If the USB subkey does not exist, create it. To do this, follow these steps:a. Select the Services key. On the Edit menu, point to New, and then click Key.
b. Type USB in the New Key #1 box to name the new key "USB."

3. Right-click USB, point to New, and then click DWORD Value.
4. In the New Value #1 box that appears, type EnIdleEndpointSupport, and then press ENTER.
5. Right-click EnIdleEndpointSupport, and then click Modify.
6. In the Value data box, type 1, leave the Hexadecimal option selected, and then click OK.
7. Quit Registry Editor.

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

APPLIES TO
  Microsoft Windows XP Service Pack 2, when used with:
        Microsoft Windows XP Professional
        Microsoft Windows XP Home Edition

I hope this helps someone whos,s newish laptop has been taking a dive rather early.