Microsoft has admitted it knew about the issue caused by USB devices and a significant decrease in the battery life of so equipped laptops and says it will soon be releasing a fix.
eWeek: The issue comes down to the way Windows XP Service Pack 2-equipped notebook PCs react to the presence of USB 2.0 devices. With a one of the devices attached, the machines basically burn more power and thus, when switched to battery power, don’t run for the same length of time on a battery charge.
The cause is rooted in the intricate way in which USB 2.0 devices interact with ACPI, the Advanced Configuration and Power Interface power management software included with Microsoft’s Windows XP Service Pack 2, hardware testers who discovered the issue report.